1、1.when 的用法 when“当时候”,从句用的最多的是一般过去时，而主句的时态没有限制,根据具体情况而定。When she came into my room,I was just reading a book.她走进我房间时，我正在看书。When I got to the airport,the guests had left.当我赶到飞机场时，客人们已经离开了。“当时候”She was about to go out for a walk when her uncle came.她正打算出去散步，就在那时她叔叔来了。She was cooking when someone knocke
2、d at the door.她正在做饭，就在这时有人敲门。就在那时 at that time 当while 事件正在发生的时候，另一件事如何,while 从句一般用的是正在进行时While my wife was reading the newspaper,I was watching TV.当妻子正在看报纸的时候，我正在看电视。While Jim was mending his bike,Lin Tao came to see him.正当吉姆修自行车时，林涛来看他。2.while 的用法 While Jim was mending his bike,Lin Tao came to see
3、him.正当吉姆修自行车时，林涛来看他。While they were talking,the bell rang.正在他们谈话的时候，上课铃响了。含有“一段时间”的含义 as 从句用的一般不用正在进行时，而只是一般过去时,一边一边”As my mother sang those old songs,tears ran down her cheeks.当我妈妈唱起那些老歌时，眼泪顺着她的脸颊流了下来。The little girls sang as they went.小姑娘们一边走，一边唱。3.as 的用法 As the time went on，the weather got worse.
4、随着时间的推移，气候更加糟糕。As years go by，China is getting stronger and richer.随着时间一年一年过去，中国变得越来越富强了。as 常常翻译成“随着”之意。如果从句动作和主句动作同时发生，并且从句动作为延续性动词时，when，while，as 可以互换使用。这种情况下，它们的细微区别恐怕连英、美人自己也说不清了。1.When/While/As we were dancing,a stranger came in.当我们跳舞时，一位陌生人走了进来。dance 为延续性动词2.When/While/As she was making a phon
5、e call,I was writing a letter.当她在打电话时，我正在写信。make为延续性动词3.While/When/As I was walking down the street,I noticed a police car in front of the bank.我顺着马路往前走时，发现银行门前停着一辆警车。when,while,as 的互换 肯定形式表示的意思是“做某事直至某时”，动词必须是延续性的。否定形式表达的意思是“直至某时才做某事”。动词为延续性或非延续性都可以。4.until和till 直到为止 肯定句：I slept until midnight.我一直睡
6、到半夜时醒了。Wait till I call you.等着我叫你。否定句：She didnt arrive until 6 oclock.她直到6点才到。Dont get off the bus until it has stopped.公共汽车停稳后再下车。His mother didnt leave until/till he was asleep.直到他睡着了，他母亲才离开。until和till Not until在句首，主句用倒装。Not until the early years of the 19th century did man know what heat is.It is
7、 not until that.It was not until I began to work that I realized how much time I had wasted.She said she would phone me as soon as she got there.她说她一到达那里就给我电话 Ill telephone you as soon as I get there.我一到达那里就打电话给.5.as soon as 一就“一就”的结构 hardly/scarcelywhen/before,no soonerthan和as soon as ,the moment/m
8、inute,都可以表示“一就”的意思.I had hardly/scarcely got home when it began to rain.刚回家，就下起雨来了。I had no sooner got home than it began to rain.As soon as I got home,it began to rain.注意：如果hardly,scarcely 或no sooner置于句首，句子必须用倒装结构。Hardly/Scarcely had I got home when it began to rain.No sooner had I got home than it
9、 began to rain.before的本意为“在之前”，根据具体语境还可理解为“还没来得及/还没有就，趁着还没。就，不知不觉就，才”等 Close the door before you leave the room.离开房间前关上门。I had not sat long before he came back.我没坐多久他就回来了 He almost knocked me down before he saw me.他几乎把我撞倒才看到我。6.before从句从句 She has never come to see me since I lived in the city.自从我住到城
10、里，她就一直不来看我。I have lived here ever since I was a child.我从还是个孩子时就一直住在这儿7.since从句从句 I went to school after I finished my breakfast.吃完早饭后我就去上学了。after“在之后”1.I havent heard from him _ he went to America 2.Do not leave the room _ you have finished the test.3.She sang _ she went along.练习 1.It was quiet _ th
11、ose big trucks started coming through the town.A.before B.after C.until D.unless 2.Hardly had he reached the school gate _ the bell rang.A.while B.when C.as D.as soon as 3.He was about to go to bed _ the doorbell rang.A.while B.as C.before D.when 4._ John was watching TV,his wife was cooking.A.As B.As soon as C.While D.Till练习
