| 家教张老师的文章列表 |
|---|
2012年12月份大学英语四级作文预测题目 [商务英语]
发表于：2012-10-26 阅读：1593次
1. Should We Help Strangers? 1. 有人认为帮助陌生人是一种美德; 2. 有人却认为帮助陌生人会给自己带来麻烦和危险; 3. 我认为…… 【范文】 Helping strangers has always been considered as a treasured virtue of mankind. We need help from others throughout our life, whenever we travel to other places or stay at home. On the other hand, helping others can make us happy. We feel great joy when we are trusted, needed and able to give a hand. However, some people are cautious when it comes to helping strangers. They say that helping others involves risks of getting hurt or cheated. Lending a hand to a stranger often puts us in a vulnerable position for it means trusting someone we do not even know. Moreover, there are times when we have physical limitations. For instance, we can’t swim but a girl is drowning, what should we do? If we are blind to that limitation, giving a hand would conversely take our life. In my opinion, we should still offer what we can do to help those needed strangers. Meanwhile, we should beware of getting cheated and use our common sense to tell whether the strangers are real needed people or just professional cheats. Detecting anything unusual, we should defend ourselves or turn to the police.
2. Don’t Rely Too Much on Computers 1. 现在许多人越来越依赖电脑; 2. 过分依赖电脑会带来很多问题; 3. 我的看法 【范文1】 Do we rely too much on computers? Yes, we do. Almost everything we do and every aspect of our life is affected by modern technology with computers above all. We use computers in business, public services, education and entertainment. However, over-reliance on computer may give rise to some problems. One is that people are more likely to make spelling mistakes when they have to handwrite something. Another is that people are so dependent on computers that they have lost the ability to think for themselves. If “the computer says XYZ”, then XYZ must be true. If you want to make yourself an idiot, just tell him “that is what the computer said”. In my opinion, computers make our lives easier but we should never rely on them completely. These machines should be used as tool to aid work rather than the only tool. Otherwise, chaos can occur when suddenly our computers crash or what is worse, refuse to take our orders.
【范文2】 With the development of science and technology, computers have played an increasingly important role in our daily life. Computers make our life more convenient. We can not only finish our essays online, but also buy some daily commodities and play games online. However, it’s estimated that people spend more than three hours on surfing the internet. Now more and more people become weak and shortsighted. It is because they surf the Internet day and night but without rest. In addition, the reason why students rely on too much on computers is that they can find many reference materials online. So students become less independent in thinking for themselves now. All in all, we can’t live without computer, but we should try to go out to do some exercise with our friends. What’s more, it is time for us to finish our assignments independently instead of finding the reference answer online.
3. TV Talent Show 1. 有人赞成电视选秀节目 2. 有人则反对 3. 我的观点 【范文1】Over the past couple of years, a variety of talent shows have emerged on TV channel across our nation, from Happy Girls to Super Boys and so forth. This type of entertainment programs is intensely popular, especially among youngsters. It has produces profound impacts on their studies and life. They believe that the TV talent show can change their fate. At least, they say, the program offers the opportunity to show and develop one’s talents. On the contrary, a number of people hold negative attitude to TV talent shows. They maintain that The TV talent show today is like a fiver that has risen to its flood level. It misleads the youth and makes them believe that they can make a fortune or become famous overnight. As a result, a great many students can’t calm down to study during the show’s season. For my part, I believe that the TV talent show is like a double-edged sword and it is important for us to face it properly. For one thing, the TV studios are supposed to offer more stimulating and favorable shows. For another, the media ought to give people proper guidance and refrain from exaggerating the effects of the show. 【范文2】 Recently, there is a public discussion about TV talent show. ,because many TV stations have all kinds of TV talent shows, such as Super Boy, Dream of China and so on. TV talent show makes a profound influence on our day-to-day life. Undoubtedly speaking, different people hold different attitudes toward TV talent show. On the one hand, a lot of people seem to think that TV talent show should be supported. The reason why they support it that it gives many people an opportunity to show their talent. And they will become famous for it in sometimes. On the other hand, others believe that TV talent show should be canceled, because many people insist that TV talent show is a speculation. It gives people a false impression that very person will be famous if they attend these shows. In addition, many young people idolize their idols. From my perspective, we should pay more attention to the advantage of TV talent show. Meanwhile, we might take some measures to avoid some negative effects of TV talent show.
4. Killing Time Indoors 1. 现在很多人业余时间喜欢“宅”在家里 2. 人们对这种做法有不同的看法 3. 我的看法 【范文】 Nowadays a growing number of people, especially the 20s or 30s, tend to stay indoors for most of their spare time, especially during holidays. Some spend the majority of their time online chatting, blogging, shopping, dating or playing computer games. Some sit with their eyes glued to the television screen, day and night. People’s opinions vary when it comes to this ways of killing time. A great number of people maintain that staying indoors is cheaper, comfortable, and most importantly, very safe. Others, however, frown upon staying indoors for too long. They are worried that lack of physical exercise and face-to-face communication with others will do harm to people’s body and mind. Personally, I don’t think staying indoors for most of the day should be advocated. Instead, people in all ages, with their physical conditions permitting, should be encouraged to spend more time outdoors. The fresh air, the brilliant sunshine, the pleasant green space, the interactions with other people, etc. are all good for people’s health, both physically and psychologically.
5. Restrict Mobile Phone in Library 1. 现在有不少人在图书馆的阅览区里使用手机 2. 这一现象可能带来的影响 3. 我的看法 【范文】 As the number of students who have mobile phones increases, various problems also rise, along with its popularity. One of the problems that have aroused students’ attention is the use of mobile phone in the reading room of library. And this phenomenon has become so common that you can always see someone using mobile phone whenever you go into the library. There is no doubt that this behavior will have no good effect. On the one hand, students who use it can not concentrate on their own studies when they constantly send or receive messages. On the other hand, with the ringing of the phones and people’s talking over the phone, students around them may be distracted from their reading as well. Therefore, the proper way of using mobile phones in the library must be emphasized. First of all, whenever you enter the library, turn your mobile phone into the mode of silence or vibration so as to avoid the disturbance of other students. Second, if you do need to make a call or send or receive messages, you’d better go out of the reading room or at least try to reduce the volume of your sound and your phone’s sound.
6. My Opinion on Micro-blog 1． 目前越来越多人开起了“微博” 2．“微博”会带来一些问题 3. 我的看法 【范文】 With the improvement of micro-blog services and the influence of some “star bloggers”, most of whom are celebrities, micro-blog is becoming an important way for people to express themselves and communicate with others. Now, more and more people start to use micro-blog services. However, micro-blog might give rise to some problems as well. Some bloggers would express their thoughts and ideas by writing them down in the micro-blogs rather than communicate with their friends or family members. Day by day, blogs tend to draw people away from real life. What’s worse, lack of face-to-face communication with others might isolate bloggers from the society, which would do harm to their mental health. In my view, micro-blog is a good platform for people to show their personal experiences and communicate with others. However, micro-bloggers should adjust the item and avoid spending the whole day on blogging. After all, sitting in front of the cold screen of computer for long does no good to their health, physically and mentally. 7. Celebrities as Products’ Spokespersons 1. 现在明星为产品代言的现象很普遍 2. 明星代言存在的一些问题 2. 我的看法 【范文】 In the contemporary society, it is very common for celebrities, or the so-called superstars to be spokesperson for a wide variety of products. On the Internet, television, newspapers, magazines and even on the walls of some buildings, you may find celebrities in the advertising posters. There are some problems existing in celebrities’ endorsing products. In the first place, some stars may know nothing about the products but still accept the invitation as their spokesperson. To these stars, “Look before leap” is just a saying. In the second place, for the sake of money, some stars advertise for items with low quality, even for fake commodities. They never care about consumers’ interests. In my view, as spokespersons, celebrities represent the products. They should understand that the products they are endorsing concern their images and consumers’ interests. Therefore, before endorsing products, they should learn about the products as much as possible. Only by doing so, can they be trusted by their fans and protect the legal rights of general public.
8. Spam Message 1. 目前垃圾短信泛滥 2. 这种现象产生的原因 3. 如何解决这个问题 【范文】 With the increasing use of cell phones, spam messages have become a heated issue. According to a survey, on average, people receive about 40 pieces of spam message per month. Spam messages may disturb, confuse, or even threaten people at any time. Generally, there are two reasons for the spam epidemic. On the one hand, due to the fact that text message is a comparatively cheap channel. Many companies take advantage of it to advertise their products or services. Whether people are willing to receive the message is neglected. On the other hand, operators, holding lots of information on cell phone users, sell the importance information and make money out of it. To solve the problem of spam message, relative authorities and professionals should make joint efforts. The government should set up laws to severely punish the illegal advertisers and those who disclose users’ information. Cell phone researchers and developers should upgrade the products and enable them to delete the spam automatically. Should people act together, they will be free from the spam message.
9. Internet Slang 1） 近年来，网络语言在青少年中很流行； 2. 人们对这一现象的看法不同； 3. 我的看法是…… 【范文】 Internet slang such as CU (see you) and 3X (thanks), enjoy great popularity among teenagers nowadays. In fact, it has become so popular that many items now cross from computer-mediated communication to face-to-face communication. Some teenagers even use them in spoken communication as well as in essay writing. People have different opinions towards this phenomenon. Some people say that the crossover is a brand new variety of language evolving and will enrich the language. But others disagree, saying that these new words, being short form for the existing, long-used phrase, don’t “enrich” anything; they just shorten it. Furthermore, even if the slang such as CU and 3X and becomes common in spoken English, their total effect on language will be trivial. In my opinion, Internet slang has little effect on language in general, but will greatly influence individuals, especially teenagers’ language development. It is because overuse of Internet slang will lead to their poor writing, being lacks in spellings, grammar and proper punctuations. That will drastically reduce chances of employment after they graduate and seek jobs. So, for the sake of their future, teenagers had better refrain from Internet slang.
10. How to Relieve Stress 1. 现代人面临着各种压力 2. 人们减压的方法各异 3. 我的减压方法是…... 【范文1】 In today’s fast-paced world and with the booming economy, stress is our constant companion. We may face stress from our jobs, families, peers, etc. Though stress adds flavor and challenge to life, too much stress can seriously affect people’s physical and mental well-being, so it is necessary to handle stress properly. When it comes to reducing stress, people vary in their ways. Some people talk with someone, perhaps a friend or a family member, about their anxieties and worries. Others allow themselves a mental “get-away”: a quiet country scene painted mentally can divert them from the tension of a stressful situation to a more relaxing frame of mind. There are also people who create a sense of peace by reading a good book. The effective way to relieve stress for me is different from those mentioned above. I have several relaxation techniques. For examples, when stress occurs, I would take a deep breath and exhale and if possible, I would take a warm bath. They prove to be very helpful. They help me to calm down my mind and improve my response.
【范文2】 Stress is an inevitable part in our life. Many kinds of big events, such as natural disasters, wars and death, can cause great stress. On a day-to-day basis, most people may be faced with stress, resulting from trivial things: taking an exam, waiting in a line, and having too many things to do within a limited time. Various ways can help people to reduce stress. Some people try physical activities which prove to be a great way of getting rid of pressure. For others, sparing time for fun, such as reading humorous books or listening to beautiful music, also helps to derive away bad moods. Still, a good cry can be an effective and healthy way to bring relief to one’s anxiety in a short time. As far as I am concerned, when stress does occur, it is important to recognize it and deal with it rather than escaping from it. My usual way to decrease stress would be practicing yoga, which helps me relax and it is good in keeping a very peaceful mind. And, I strongly oppose the negative ways such as taking sleeping pills, drinking heavily or fighting.
11. Is Military Training Necessary Now? 1. 有人认为现在的大学生军训没必要 2. 有人则认为有必要 3. 我认为…… 【范文1】 Whether military training is still necessary for freshmen has become a heated topic in China recently. Some people maintain that it is not and should be canceled. For one thing, military training is nothing but kind of torture, causing horrible sudden death time and again. For another, the training seems ineffective since most students resume their idling lifestyles at the end of the training. However, other people believe that military training is a must for today’s spoiled youth. First of all, it makes them more likely to persist instead of escaping in face of hardships. Second, the self-discipline and teamwork spirit students develop are invisibly valuable wealth for their future. Last but not least, it provides a good chance for students to learn more on military and broaden their horizons. Generally, I agree with those advocating for military training. However, I insist that some training programs should be modified or carried out carefully. For example, when trainees have to stand for hours in the hot sun, trainers and teachers should watch closely their physical conditions to prevent the tragedy of sudden death from happening. 【范文2】 Is it necessary for universities to hold military training for the freshmen now? Different people have different opinions. The opponents say it is a waste of time because what the students learn from it is of no use to their real life. Besides, they also worry about the safety due to the increasing cases of students who got injured or died in it. However, the supporters hold the view that the military training is very beneficial. They believe that it can nurture students’ sense of unity and discipline and foster students’ patriotism as well. What is more, the advocators regard the military training as a good chance for students coming from different cities to know and help each other, which will help them ease the feeling of homesickness. Personally, I think the military training is not a bad thing if effective measures are taken to avoid the potential risks involved in it. With careful consideration and preparation, it can not only have a good influence on students’ character, but also help students learn how to cooperate with other people.
12. Whom Do You Turn to When in Trouble? 1. 有人遇到困难时向同学、朋友求助 2.有人则向老师、家长求助 3.以你自己为例…… 【范文】 Just as the saying goes: life is not all roses, all of use will need someone else’s help to deal with problems that we may encounter in our life. Here comes the question: whom will you turn to for help? Some say they will ask their classmates or friends for help, because they are peers, thus they can understand each other easily. However, others have different choices when in trouble. They are inclined to tell their teachers and parents the difficulties they are faced with. In their opinion, teachers and parents, who are much older than them, can give them a hand with their rich experience. As for me, close friends are always the people who come to my mind firstly when I am intrigued by something that can not be solved by myself. If we can not figure out a solution by our joint effort, I will go to my teachers or parents for help. With their suggestions or instructions, I can finally find the best way to cope with my troubles.
13 On Self-employment of College Graduates 1. 政府加大了鼓励大学毕业生自主创业的力度； 2. 产生这一现象的原因； 3. 我的看法是…… 【范文】 Nowadays many college graduates set up their own companies with the fund from the government, which is part of the plans to help graduates to get employed. If graduates can put forward a creative and original plan, they will get the financial aid from the government. Our government is paying increasing attention to this program. There are many reasons responsible for this program. It is intended to stimulate college graduates’ creativity and relieve their pressure of employment. First, there has been an expansion in universities and colleges. As a result, the rate of unemployment is on the rise in recent years because of the competitive job market. Second, some graduate employees are not satisfied with their present jobs and their enthusiasm for work has been frustrated, so they can’t exhaust their potentials. Third, some brilliant and ambitious graduates are confronted with a shortage of start-up capital, so they find it hard to apply what they learn to practice, no matter how good their idea sounds. As far as I’m concerned, the program will not only offer opportunities to graduates but also bring back their confidence in themselves and in the future. An increasing number of graduates will benefit from this program. What is more, the development of each graduate will surely promote the development of the whole society in the long run.
14. Text Messages on TV Shows 1 目前各类电视节目广泛使用短信参与方式 2. 人们对此有不同的看法 3. 我认为……. 【范文】 At present, text messages are widely used in various TV shows. From serious news programs to different kinds of entertainment programs, we can always see some interactive sessions which all include the use of text messages, such as text-message voting in Super-girls and Happy boys. Is it good or bad? Some people hold the view that it provides a convenient and relatively cheaper way for audience to participate in the program. While others think it is nothing but a method which takes advantage of the public’s curiosity and their hope of winning awards to lure them into sending lots of messages that cost them a large amount of money. As far as I’m concerned, text message is an effective medium for the audience to interact with the TV shows, which can arouse people’s passion for watching the programs, and bring benefits to the TV station as well. But when we are enjoying the merit of it, we should also take the contents and objectives of the TV programs into consideration to ensure the quality of the TV shows.
15. Attending Your Classes Regularly 1. 大学生迟到、早退、旷课现象越来越普遍； 2. 保证学生的出勤率对大学教育的重要性； 3. 作为大学生，我们应该…… 【范文1】 In recent years, with the admission expansion of colleges and universities, there exists a common phenomenon that an increasing number of students are late for or even absent from classes, and a few students even slip out of the classroom before the teacher end up the class. The class attendance is becoming one major problem waiting for immediate attention. There is no doubt that class attendance is of crucial importance to students’ development. In the first place, if students fail to attend the class timely, they will surely miss what the teacher adds to the textbook. In the second place, they demonstrate a lack of self-constraint which plays a vital part in their future. What is worse, they will definitely influence the smooth progress of the class, and his classmate fall victims to his violation of rule. As college students, we should bear in mind that “Well begun is half done” and “Habits make nature”. If we can develop a good habit and prevent ourselves from violating the rule, even the most trivial one, we will certainly strive straight toward the target we have in mind. We should learn to discipline ourselves on campus; otherwise we may suffer a lot in our work place in the near future. You might lose your job or opportunity if you were late.
【范文2】Attending Your Classes Regularly “Should we attend our classes regularly” is an unchanged topic in the university. It is universal that college students are eager to leave early and skip classes frequently. It’s because some students think the classes are so boring that they choose to skip classes. Others are busy in their own association activities, so they have to play truant. However it would give rise to a lot of problems. For instance, some students can’t pass the final exam for skipping classes frequently. What’s really matter is that they will miss plenty of professional courses which will play an important role in their future job. Taking from all the evidence into considerate, we can safety come to the conclusion that we can’t only study without participating in other association. But at the same time we should use our schedule flexibly to balance our academic and spare time. Otherwise teachers should put an emphasis on the improvement of their teaching style which can attract students to listen to their courses. Only in this way can school ensure students’ attendance. 【范文】 Nowadays, the phenomenon of university students being late for class, left class early and cut class has become a problem we have to face. This phenomenon is more and more common in college. And a number of students are accustomed to do it. Eventually, many students believed that university life is not perfect if you never miss class. A number of factors might contribute to the phenomenon. It is a high time that we put an end to the trend. It is important to pledge the attendance rate of students. The attendance rate of students is representing students’ learning attitude. A high attendance rate not only let students learning more knowledge but also gives some encouragement to teachers. It is beneficial for students to develop a good habit. As a college student, I had been late for class. Even though we have many reasons to do it. Obviously, it is a wrong behavior because it is bad for our study. Eventually, it wastes our time and money.
16. Campus Certificate Craze 1）大学生“考证热”成为潮流； 2）出现这种现象的原因； 3）你的看法是…… 【范文】 If you just stop student on campus and ask him what he is busy about, chances are that he will tell you he is preparing for a certificate of some kind. Investigation points to the fact that it has become a new craze for university and college students to get more certificates. There are two main reasons for this phenomenon. To begin with, university and college students are faced with the pressure of finding a job after graduation. With the admission expansion of colleges, a lot more graduates have to compete for the limited jobs posts. How could one be more competitive? More certificates will doubtlessly impress the employers, so the students are compelled to run from one exam to another. Besides, more and more universities and colleges modify their education training which includes several creative credits. If students fail to get such credits, they can not graduate. As a result, most students choose to pursue certificates. As far as I am concerned, the students should have a more rational attitude toward certificate, because such certificates do not necessarily represent one’s ability. For me, inner ability speaks louder than certificates, which can only be compared to appearance. Opportunities only arise when you are excellent enough in your field.
17. A Brief Introduction to the University 假设你是一名学生志愿者，要给来你们学校参观的外国朋友介绍学校情况。内容应包括学校历史、规模、教学现状以及未来目标等。 【范文】 Distinguished guests， Welcome to our university. Before you start to look around，allow me to give you a brief account of the school. Founded in 1927，our university is one of this city’s earliest universities of liberal arts. It is staffed with an excellent faculty，and has a total enrollment of over 10，000 students. In the past years，it has turned out numerous well-qualified students and found its graduates active in professions of all walks of life. Since its establishment，the university has always steered itself toward the objective that its students have an overall healthy development. Not only does it provide the students with basic academic courses， but it manages to expose them to the up-to-date knowledge. Besides， students are free to participate in colorful campus activities and social practice， which are intended for broadening their mind and developing their potential talent. Currently， both our faculty and students are making every effort to improve the quality of our education in the direction of a first-rate university. Thank you.
18. Directions： For this part， you are allowed 30 minutes to write a letter to a friend who will come to your city to see you. You should write at least 120 words following the outline given below in Chinese： 假设你是李明， 你的一个朋友张伟准备到你所在的城市来旅游，但你有事不能接待。写封信给他，解释你不能接待的原因，并说明你所做的安排。 【范文】 A Letter to a Friend Dear Zhang Wei， I’m glad to know that you are coming to my city during the summer vacation. However，I’m afraid there’s some bad news. I’m planning to take part in an international conference to be held in another city during the time of your visit. All the top scientists in my field will show up at the conference. More importantly，I’m lucky enough to have been selected to give a speech on behalf of my research team at the Conference. I really can’t miss it. I understand that it’ll be your first time to this city and I’m your only friend here. I’ve asked my roommate to meet you at the airport， and you can stay in my room. He is a very nice person and he will show you around the city. Hope you two will get on well and have a nice holiday！ Yours， Li Ming 19. Directions: Suppose you are required to write a Want Ad for the Dean. You are supposed to base this ad on the outline given below: sessions 【范文】 The office of Dean of students is looking for a Student Consultant to the Dean for the upcoming academic year.
20. 假设你过生日时收到了Lucy送来的鲜花，写信向她表示感谢。 你的信应包括: 1. 表达感谢之意 2. 提出回报对方 3. 期待对方做客 【范文】 Dear Lucy, I am writing to express my sincere thanks for your beautiful flowers. I’d like you to know how much your flowers meant to me. You have a positive genius for selecting the right gift. I not only enjoyed your flowers, but also the delicate vase. I shall ever remember this gift as one of the most precious things in my life. I will not be very busy the following days. I hope to have the opportunity of reciprocating. Would you kindly let me know what time you are at convenience? I will feel very happy if you have time to make me a call. How nice it would be to see you again and I am looking forward to seeing you next time! I repeat my thanks again for your lovely flowers. Please give my kind regards to your family. Yours truly, Huck 21. Ａ Letter of Job Application 【范文】I am writing the letter to show my keen interest in the post of assistant manager which you advertised in Southern Daily for. As is indicated in the enclosed resume, my major and experience closely parallel your requirements. In my opinion, I think it is reasonable to maintain that we should be careful when helping strangers; but it is foolish to claim that it is not necessary to help strangers who are really in need. All in all, we should help the strangers. What’s more, it’s high time the authority took effective measure to establish a sound system to perfect the credit system. Only in this way can we live in a harmony society. I would like to meet you at your convenience. Thank you for your time and consideration. 22. How to Succeed in Passing CET-4? 【范文】 Nowadays, English has become a universal language. It is quite necessary for us to learn English well. In China, CET -4 plays an important role in job-hunting. Many companies require candidates to have CET4 certificate or higher scores in the results of CET-4. So it is crucial for university graduates to pass the CET4 successfully. How to Succeed in Passing CET-4? It is no doubt that English level is very important factor. In addition, test-taking strategies are the key to succeed in passing CET4.We should get familiar with the general requirements and basic test-taking skills in Writing, reading, listening and other items. We should try our best to learn English and find the best way to get a high mark. Learning English really takes time so if we want to learn it well, we should spend much time practicing using English every day. Besides, we should listen to the teachers and take notes carefully in class. Go over what is learnt regularly and finish doing our homework carefully. If we have time, we'd better listen to English radio programs, read English stories and newspapers, watch English films and TV programmers, keep a diary in English. If we make mistakes, correct them at once and try not to make the same mistakes. What's more, we should look up new words in the dictionary before class and prepare each lesson carefully before class. I believe if we work hard and have good ways of learning English, we can pass the CET4, and get a high mark. Personally what I suggest is that，if you really what to succeed in passing CET4，you should，first of all，remember three very important words—confidence，determination and perseverance. That is，whatever we do，we should always believe in ourselves，and once we have made up our mind to do something，we should try our best to do it well. What’s more，no matter what difficulties we may come across，we should not be discouraged，nor should we give up. Instead，we should keep on trying until we succeed. All in all, passing CET4 is on our own, we worked hard to be successful only. 本段非常精彩，句型应用恰如其分！
|
初一（3）部数学有理数计算练习题 [初中数学]
发表于：2012-10-25 阅读：306次
1、 2、 3、 4、 5、（— ）÷（—16）÷（—2） 6、 –4 + 2 ×(-3) –6÷0.25 7、（—5）÷［1.85—（2— ）×7］ 8、 18÷{1-[0.4+ (1-0.4)]×0.4 9、1÷( - )× 10、 –3-[4-(4-3.5× )]×[-2+(-3) ] 11、 8+(- )- 5- (- 0.25) 15、 ; 16、 17、 + －4.8 18、 19、 + 20、 21、100 22、(－3 )÷(4 －12 )÷(－ )×(－1 ) 23、(－2)14×(－3)15×(－ )14 27、 24、－42＋5×(－4)2－(－1)51×(－ )＋(－2 )÷(－2 ) 25、－1 ×3 －1 ×4 －3×(－1 ) 26、 55、 56、 60、 57、 62、 58、 69、 59、 70、 66、 67、 68、 71、 121、 78、 79、 81、 |
绝对值与一元一次方程 [初中数学]
发表于：2012-10-22 阅读：771次
【例1】方程│5x+6│=6x-5的解是_______.(2000年重庆市竞赛题) 思路点拨 设法去掉绝对值符号,将原方程化为一般的一元一次方程来求解. 解:x=11 提示:原方程5x+6=±(6x-5)或从5x+6≥0、5x+6<0讨论. 【例2】适合│2a+7│+│2a-1│=8的整数a的值的个数有( ). A.5 B.4 C.3 D.2 (第11届“希望杯”邀请赛试题) 思路点拨 用分类讨论法解过程繁琐,仔细观察数据特征,借助数轴也许能找到简捷的解题途径. 解:选B 提示:由已知即在数轴上表示2a的点到-7与+1的距离和等于8,所以2a表示-7到1之间的偶数. 【例3】解方程: │x-│3x+1││=4; (天津市竞赛题) 思路点拨 从内向外,根据绝对值定义性质简化方程. 解:x=- 或x= 提示:原方程化为x-│3x+1=4或x-│3x+1│=-4 【例4】解下列方程: (1)│x+3│-│x-1│=x+1; (北京市“迎春杯”竞赛题) (2)│x-1│+│x-5│=4. (“祖冲之杯”邀请赛试题) 思路点拨 解含多个绝对值符号的方程最常用也是最一般的方法是将数轴分段进行讨论,采用前面介绍的“零点分段法”分类讨论;有些特殊的绝对值方程可利用绝对值的几何意义迅速求解. 解:(1)提示:当x<-3时,原方程化为x+3+(x-1)=x+1,得x=-5; 当-3≤x<1时,原方程化为x+3+x-1=x+1,得x=-1; 当x≥1时,原方程化为x+3-(x-1)=x+1,得x=3. 综上知原方程的解为x=-5,-1,3. (2)提示:方程的几何意义是,数轴上表示数x的点到表示数1及5的距离和等于4,画出数轴易得满足条件的数为1≤x≤5,此即为原方程的解. 【例5】已知关于x的方程│x-2│+│x-3│=a,研究a存在的条件,对这个方程的解进行讨论. 思路点拨 方程解的情况取决于a的情况,a与方程中常数2、3有依存关系,这种关系决定了方程解的情况,因此,探求这种关系是解本例的关键,运用分类讨论法或借助数轴是探求这种关系的重要方法与工具,读者可从两个思路去解. 解:提示:数轴上表示数x的点到数轴上表示数2,3的点的距离和的最小值为1,由此可得方程解的情况是: (1)当a>1时,原方程解为x= ; (2)当a=1时,原方程解为2≤x≤3; (3)当a<1时,原方程无解. |
冠词的应用 [高中英语]
发表于：2012-10-14 阅读：506次
冠词 基本用法：不定冠词表泛指；定冠词表特指。 重点关注：冠词的基本用法、不用冠词的情况、某些名词前使用冠词与不使用冠词的不同含义、固定短语中的冠词用法、在感叹句型或比较句型中考查冠词、在特定的语境中活用冠词。 一． 不定冠词的基本用法 a / an 1．用于可数名词单数形式前，表示“一个”人和物。A stitch in time saves nine. 2．表示一类人和物。A lion can be dangerous. 3．表示“某一个”的意思。A gentleman wants to see you. 4．表示“同一”的意思。They are nearly of an age./ The two shirts are much of a size. 5．表示“每一”的意思。We go swimming four times a week. 6．用在作表语、同位语的单数可数名词前，表示身份、职业。My mother is a lawyer. 7．第一次提到的人或事物，但不特别指明是哪一个。Long long ago, there was an old king who had a very beautiful daughter. 8．用在某些表示数量的词组中：a lot of; a couple of; a great many; a dozen, one dozen; a great deal of. 9.用在某些抽象名词前，该抽象名词前便具体化了。 He has a knowledge of chemistry. The get-together was a great success. 一、 定冠词的基本用法 1．用以表示一个特定的人或物。We have to wait for the next bus. 2．用于指谈话双方都明确所指的人或物。Open the door, please. 3．用以复述上文提过的人或物（第一次提到用a 或 an，以后再提到用the ）Once there lived a lion in the forest. Every day the lion asked small animals to look for food for him. 4．用在序数词和形容词最高级前。January is the first month of the year. Shanghai is the biggest city in China. 5．表示世界上宇宙中独一无二的事物。the sun; the moon; the earth; the sky; the world. 6．一些由普通名词构成的专有名词 the West Lake; the Great Wall; the United States; the United Nations 7．表示方向、方位。in the east; in the west; in the front; at the back; in the bottom; at the top; on the right; on the left. 8．在海洋、江河、湖泊、山脉、海峡、海湾等地理名词前 the Pacific Ocean; the Huanghe River; the Taishan Mountains; the Taiwan Straits 9．在姓氏复数前，表示一家人 The Bakers came to see me yesterday. 10． 和某些形容词连用，代表一类人或物。the poor; the rich; the sick; the wounded; the good; the beautiful. 11.表示演奏乐器时，乐器的前面要加the. play the piano; play the violin 二、 零冠词的用法 1．专有名词前一般不加冠词China; Europe; Lei Feng; William Shakespeare 2.月份、周日节日前一般不加冠词。January; Sunday; Christmas Day; Thanksgiving; National Day; May Day 3.三餐、四季前一般不加冠词。I have lunch at school. Summer is the best season for swimming. 4.进行球类运动。play basketball, play volleyball, play football. 5.没有特指的物质名词、抽象名词和复数名词前。The cart is made of wood. Time is precious. 易错（混）考点解读 一、 用a与用the 含义不样； in a way/in the way; a number of/ the number of; for a moment/ for the moment; a second time/ the second time; at a time/at the time; 二、 冠词的特殊用法 1．抽象名词具体化。 其前可用a/an.。a surprise/pleasure/success/failure; an honour/experience. Oh, John. What a pleasant surprise you gave us! 2．用于物质名词前，表示“一场、一种、一份”等。A heavy rain fell yesterday. I would like a coffee and two beers. 3.用于专有名词前A John called during your absence. I remember he came here on a Sunday and left soon. 4．用于序数词前，表示“再一”或“又一”。I have to buy a second hat. He thinks himself a second Napoleon. 5．用在most 前，表示“非常、十分”。It’s a most moving story. 6．用在the more, the better 比较级的句式中。The more you drink, the more you like it. 7．用在句型“动词+ sb. +介词+ the + 身体的某一部位”中. Take sb. by the arm, hit sb. in the face, be lame in the right leg. 8．用在度量单位的名词前I have hired the car by the hour(by time). Eggs are usually sold by the dozen in the west. 三、冠词使用应注意的几个问题。 1．冠词的位置 （1）a/an + adv. +adj.+ noun He is an honest man. (2 ) such/what/quite/rather/half/many+ a/an+ adj.+ noun The news gave me such a shock.. (3) 在so/as/too/how/however + 形容词后。 I’ve never seen so beautiful a girl. (4) half/twice/three times + the + 名词 Their house is twice the size of yours. 2.冠词的省略 (2 )turn + 单数可数名词前一般不用冠词。He was a miner before he turned writer. (3)在单数名词+as/though +主语+ is/was的让步状语从句中。Fool as he is, he will not do such a thing. (4) 单数可数名词表示独一无二的职位、身份、头衔。He was elected monitor of our class 练习 ( ) 1.______recent report stated that the number of Spanish speakers in the U.S .would be higher than the number of English speaker by_____ year 2090.A, the B. A, / C. The ,/ D. The, a ( ) 2.If you go by ______train ,you can have quite a comfortable journey ,but make sure you get _____fast one. A. /, / B./, a C. the, a D./,/ ( ) 3. It is often said that ____teachers have _______very easy life. A /,/ B. /,a C. the,/ D. the, a ( ) 4.I can’t remember when exactly the Robinsons left _____city ,I only remember it was ______ Monday.。 A. the , the B. a ,the C. a, a D. the, a ( ) 5.If you grow up in ______large family ,you are more likely to develop _____ability to get on well with ______others .A. /,an the B. a, the ,/ C. the ,an ,the D. a, the ,the ( ) 6.Mrs ,Taylor has ___8-year-old daughter who has _____gift for painting –she has won two national prizes. A a, a B. an ,the C. an ,a D. th ( )7.Afetr dinner he gave Mr. Richardson ________ride to ________Capital Airport. A .the, a B. a the C. /, a D. /, the ( )8.On May 5,2005,at ___World Table Tennis Championship ,Kong Ling hui and WangHao won the gold medal in men’s with ____score of 4:1. A. a ,a B. / the C. a ,/ D. the ,a ( )9.I knew ______John Lennon ,but not ____famous one. A. /,a B. a ,the C. /,the D. the, a ( )10.The book tells ____life story of John Smith ,who left _______school and worked for a newspaper at the age of 16. A. the, the B. a , the C. the./ D. a,/ ( )11.When you come here for your holiday next time, don’t go to _____hotel ; I can find you ______bed in my flat.A the ,a B. the,/ C. a ,the D. a,/ ( )12.If you buy more than ten, they will knock20pence off________. A. a price B. price C. the price D. prices ( )13.____on-going division between English –speaking Canadians and French-speaking Canadians is _______major concern of the country. A The ,/ B. The ,a C. An ,the D. An,/ ( )14.When he left _____college ,he got a job as ______reporter in a newspaper office . A. /, a B /, the C .a the D .the, the ( )15The most important thing about cotton in history is ___part that it played in ____Industrial Revolution. A. /,/ B. the,/ C. the , the D. a ,the |
浅谈如何学好高中数学 [学习经验]
发表于：2012-10-12 阅读：36次
进入高中以后,有不少同学不能适应数学学习,进而影响到学习的积极性,甚至成绩一落千丈。而高一又是数学学习的一个关键时期,许多小学、初中数学学习的佼佼者,进入高中阶段,第一个跟斗就栽在数学上。对众多初中数学学习的成功者,进入高中后数学成绩却不理想,数学学习屡受挫折这一现状,我进行了深入的思考。下面我就怎样学好高中数学谈几点建议，供参考:
2.思维方法的跃迁 高一学生产生数学学习障碍的另一个原因是高中数学思维方法与初中阶段大不相同。初中阶段,很多老师为学生将各种题建立了统一的思维模式,即使是思维非常灵活的平面几何问题,也对线段相等、角相等分别确定了各自的思维套路。因此,初中学习中习惯于这种机械的、便于操作的定势方式,而高中数学在思维形式上产生了很大的变化,正如上节所述,数学语言的抽象化对思维能力提出了更高的要求。当然,能力的发展是渐进的,不是一朝一夕的事,这种能力要求的突变使很多高一新生感到不适应,故而导致成绩下降。高一新生一定要能从经验型抽象思维向理论型抽象思维过渡,最后还需初步形成辩证型思维。
二、如何学好高中数学 1.转变旧观念培养数学悟性 初中阶段，弄清课本例题，通过大量练习，就可使同学们的成绩有显著的提高。这是因为初中数学内容少，相对浅显，易于掌握，而高中数学，知识点广泛，内容繁多，系统性强，节奏又快，许多同学仍照搬初中的一套学习方法，结果成绩不升反降。所以同学们必须转变旧观念，要学好高中数学必须注重培养数学悟性。悟性是什么?悟性是对课本知识的透彻理解，是对解题方法的融会贯通，是对数学问题的敏锐感觉，是对数学思想的深刻领悟。 2.克服心理障碍激发学习兴趣 一部分学生由于底子薄或学习方法不当，考试屡考屡败，从而对数学学习产生了厌倦、畏惧、困惑、依赖等心理障碍。久而久之，这些学生对学习数学缺乏热情，形成恶性循环。如何解决这一难题呢?同学们可以先从浅显的问题入手，易于顺利解答，从中体验解题成功的喜悦，从而树立了信心，激发了学生强烈的求知欲和奋发向上的决心，也就进入了良性循环，同学们就会愈学愈好。 3.注重数学思想和方法 解决高中数学闯题的法宝就是数学思想和方法。数学思想是同学们思考问题的思想指南，是理论基石。高中数学必须掌掘的数学思想：函数与方程的思想，转化与化归的思想，数形结合的思想，分类讨论的思想。数学方法是帮助同学们解决数学问题的有效方法、有力手段。高中数学运用的数学方法主要有：配方法，换元法，待定系数法，赋值法，图象法。 4.培养良好的学习习惯 学习习惯对学生数学成绩的影响起决定作用，因此，大家要注重培养良好的数学学习习惯。学习习惯的养成重在平时，贵在坚持。同学们应从以下几个方面着手。
②上课专心听讲，提高课堂效率 听课要专心致志，精力集中。重点解决预习中的疑问，及时回答老师的提问，培养思考的同步性。特别要注意老师讲解时强调的数学思想和数学方法。多问为什么要这样思考，这样的方法是怎样产生的。一些喜欢我行我素的同学，上课看资料或做题，下课借别人笔记抄，更有甚者上课经常开小差，课后再花气力去弥补，这些做法只会事倍功半。高中数学与初中数学就是不一样，知识和能力上都有很强的连贯性，有的还有一定坡度。如果不用心听课，或者时而听，时而开小差，那么效率可想而知。 ③记好笔记，总结归纳提高 记好笔记并不是把老师讲课的内容全盘复制，因为这样做会跟不上老师的节奏，从而无暇思考，影响听课效率。同学们需要记的是一些典型的例题，关键的方法，重要的数学思想。 ④精做习题，提高解题能力 有些同学认为，上课专心听讲，记好笔记就够了。其实，高中数学必须通过大量的习题训练，在做题中提高自己的思维能力、计算能力，从而达到熟练解题、举一反三、触类旁通的作用。 参考文献：
[2]《高效课堂22条》山东出版集团2009年5月第1版
|
浅谈如何学好高中数学 [学习经验]
发表于：2012-10-12 阅读：19次
进入高中以后,有不少同学不能适应数学学习,进而影响到学习的积极性,甚至成绩一落千丈。而高一又是数学学习的一个关键时期,许多小学、初中数学学习的佼佼者,进入高中阶段,第一个跟斗就栽在数学上。对众多初中数学学习的成功者,进入高中后数学成绩却不理想,数学学习屡受挫折这一现状,我进行了深入的思考。下面我就怎样学好高中数学谈几点建议，供参考:
2.思维方法的跃迁 高一学生产生数学学习障碍的另一个原因是高中数学思维方法与初中阶段大不相同。初中阶段,很多老师为学生将各种题建立了统一的思维模式,即使是思维非常灵活的平面几何问题,也对线段相等、角相等分别确定了各自的思维套路。因此,初中学习中习惯于这种机械的、便于操作的定势方式,而高中数学在思维形式上产生了很大的变化,正如上节所述,数学语言的抽象化对思维能力提出了更高的要求。当然,能力的发展是渐进的,不是一朝一夕的事,这种能力要求的突变使很多高一新生感到不适应,故而导致成绩下降。高一新生一定要能从经验型抽象思维向理论型抽象思维过渡,最后还需初步形成辩证型思维。
二、如何学好高中数学 1.转变旧观念培养数学悟性 初中阶段，弄清课本例题，通过大量练习，就可使同学们的成绩有显著的提高。这是因为初中数学内容少，相对浅显，易于掌握，而高中数学，知识点广泛，内容繁多，系统性强，节奏又快，许多同学仍照搬初中的一套学习方法，结果成绩不升反降。所以同学们必须转变旧观念，要学好高中数学必须注重培养数学悟性。悟性是什么?悟性是对课本知识的透彻理解，是对解题方法的融会贯通，是对数学问题的敏锐感觉，是对数学思想的深刻领悟。 2.克服心理障碍激发学习兴趣 一部分学生由于底子薄或学习方法不当，考试屡考屡败，从而对数学学习产生了厌倦、畏惧、困惑、依赖等心理障碍。久而久之，这些学生对学习数学缺乏热情，形成恶性循环。如何解决这一难题呢?同学们可以先从浅显的问题入手，易于顺利解答，从中体验解题成功的喜悦，从而树立了信心，激发了学生强烈的求知欲和奋发向上的决心，也就进入了良性循环，同学们就会愈学愈好。 3.注重数学思想和方法 解决高中数学闯题的法宝就是数学思想和方法。数学思想是同学们思考问题的思想指南，是理论基石。高中数学必须掌掘的数学思想：函数与方程的思想，转化与化归的思想，数形结合的思想，分类讨论的思想。数学方法是帮助同学们解决数学问题的有效方法、有力手段。高中数学运用的数学方法主要有：配方法，换元法，待定系数法，赋值法，图象法。 4.培养良好的学习习惯 学习习惯对学生数学成绩的影响起决定作用，因此，大家要注重培养良好的数学学习习惯。学习习惯的养成重在平时，贵在坚持。同学们应从以下几个方面着手。
②上课专心听讲，提高课堂效率 听课要专心致志，精力集中。重点解决预习中的疑问，及时回答老师的提问，培养思考的同步性。特别要注意老师讲解时强调的数学思想和数学方法。多问为什么要这样思考，这样的方法是怎样产生的。一些喜欢我行我素的同学，上课看资料或做题，下课借别人笔记抄，更有甚者上课经常开小差，课后再花气力去弥补，这些做法只会事倍功半。高中数学与初中数学就是不一样，知识和能力上都有很强的连贯性，有的还有一定坡度。如果不用心听课，或者时而听，时而开小差，那么效率可想而知。 ③记好笔记，总结归纳提高 记好笔记并不是把老师讲课的内容全盘复制，因为这样做会跟不上老师的节奏，从而无暇思考，影响听课效率。同学们需要记的是一些典型的例题，关键的方法，重要的数学思想。 ④精做习题，提高解题能力 有些同学认为，上课专心听讲，记好笔记就够了。其实，高中数学必须通过大量的习题训练，在做题中提高自己的思维能力、计算能力，从而达到熟练解题、举一反三、触类旁通的作用。 参考文献：
[2]《高效课堂22条》山东出版集团2009年5月第1版
|
