在把brush one’s teeth（刷牙）这个短语放到句子中间时，应该把one’s改为与主语同人称的形容词性物主代词，具体用法是：如果主语是I(我)，就把one’s改为my；如果主语是you 就把one’s改为your； 如果主语是（或者相当于）he就把one’s改为 his； 如果主语是（或者相当于）she 就把one’s改为her ；如果主语是（或者相当于）it ，就把one’s改为its ；如果主语是we ，就把one’s改为our ；如果主语是（或者相当于）they ，就把one’s改为their。例如：I brush my teeth every morning.我每天早晨刷牙。You brush your teeth every morning.你每天早晨刷牙。He brushes his teeth every morning.他每天早晨刷牙。She brushes her teeth every morning.她每天早晨刷牙。We brush our teeth every morning.我们每天早晨刷牙。They brush their teeth every morning.他们每天早晨刷牙。My brother brushes his teeth every morning.我的弟弟每天早晨刷牙。（My brother相当于he）My mother brushes her teeth every morning.我的妈妈每天早晨刷牙。（My mother相当于she）His brother and sister brush their teeth every morning.他的弟妹每天早晨刷牙。（His brother and sister相当于they）