while的用法？
while 一段时间；当……时（和……同时）；却（1）I”ll be back for a while（2）He fell asleep while doing homework.（3）John was dressed in brown while Mary was dressed in blue连词while大致有以下四种用法:1.引导时间状语从句,意为"当……的时候;和……同时",此时的主从句谓语动作同时发生,从句谓语通常是延续性动词。如:Mary watched TV while she ate her supper.玛丽边吃饭边看电视。While she was listening to the radio, she fell asleep.她听着收音机睡着了。while引导从句时,如主从句的主语一致,且从句谓语又含有be,则从句主语和be可省略。while后可直接跟现在分词、名词、形词或介词短语。如:We are teachers while (we are) serving as students.我们边当老师边当学生。While (he was) yet a youth, he gained many prizes.他年轻时就曾多次获奖。He caught a cold while(he was) on vacation.他度假时患了感冒。2.表示对比或转折,意为"而;然而"。此时,while一般位于句中。如:Some people waste food while others haven't enough.有些人浪费粮食,然而有些人却吃不饱。You like sports, while I prefer music.你喜欢体育,而我更喜欢音乐。3.表示让步,通常位于句首,意为"尽管;虽然"。如:While I agree with your reasons, I can't allow it.尽管我同意你的理由,但我不能允许这样做。While he loves his students, he is very strict with them.虽然他爱他的学生,可是他对学生们很严格。While (he was) respected, he is not liked.他虽受人尊敬,但并不被人喜欢。4.表示条件,意为"只要",其意思和用法相当于as long as。while可位于句首,也可位于句中。如:You don't have to worry while we are here.只要我们在,你就别着急。There will be life while there is water and air.只要有空气和水,就有生命。While there is life, there is hope.留得生命在,不怕没希望。5.意为"同时;也"。如:While the book is welcomed by schol-ars, it will make an immediate appeal to the general readers.这本书受到学者的欢迎,同时也会引起一般读者的兴趣。6.意为"趁着"。如:Make hay while the sun shines.晒草要趁阳光好。(谚)Strike while the iron is hot.趁热打铁。(谚)While the roses are yet in bloom, will you come with me to see them?趁着玫瑰花还开着,你和我一道去看看好吗
