before,after,until的用法与区别?

before,after,until的用法与区别?
before,after,until的用法与区别?

before,after,until的用法与区别?
before 在...以前 after 在...以后 until 直到
before的用法：
1． before用作连词时,意思是“在……之前；还没来得及 …… 就”.例如：
Before she could move,she heard a great noise,which grew to a terrible roar.她还没来得及动弹,就听见有很响的声音,接着就成了可怕的隆隆轰鸣声.
Before I could say a word,she had stormed out of the room.不等我说一句话,她就冲出了房间.
Don’t count your chickens before they are hatched.不要高兴得过早.
2． 用于It + be + 时间段 + before...句型中,意思是“在……之后才……”.例如：
It will be five years before I come back.
我五年后才能回来.
after用法:
(1)介词:
(a) Please come to my house after dinner.晚饭后
(b) He ran after the bus.追赶
(c) His mother waited for him night after night.（一个）接着（一个）
(d) It's sad to fail after all that work.由于
(e) They are still friends after all their differences.
(2) 副词:
(a) three hours after; (b) departed shortly after; (c) after all I don't really know him.终究
(d) He told me afterwards that he had not enjoyed the film.后来
(3)连词:
(a) I saw them after I arrived.后来
(b) They arrived soon after.后来
(c) tomorrow,or the day after...
(4) 名词:
(a) afternoon午后; (b) afterthought事后的想法; (c) aftermath后果
until的用法
until可用作介词或连词,意为“到……时候为止”、“到……时候才”或“在……时候以前不”.
1.如果主句中的谓语动词是终止性动词,应采用“...not ...until ...”结构,意为“……到……时候才……”.例如：
You mustn’t eat anything until you see the doctor.看过医生之后,你才能吃东西.
2.如果主句中的谓语动词是延续性动词,那么谓语动词用肯定式或否定式,它们所表达的意思有所不同.
1） 如果谓语动词为肯定式,则until译为“到……时候为止”.例如：
I watched TV until she came back.我看电视一直看到她回来.
2） 如果谓语动词为否定式,则until应译为“到……时候才”,即“在……以前不”.如：
I did not watch TV until she came back.（= I began to watch TV when/after she came back.） 直到她回来我才开始看电视.
3.用终止性动词作谓语时,until既可以和not连用,又可以和never,nobody,nothing,few,little,seldom,hardly等含否定意义的词连用.例如：
I had not seen him until 1990.（= I had never seen him until 1990.） 1990年以前我从未见过他.
Don’t put off until tomorrow what you can do today.（= Never put off what you can do today till tomorrow.） 今日事,今日毕.