1、 时间状语从句when 、 while、 as、 after、 before、 as soon as 、since、 till /until、 by the time 在时间状语从句中，要注意时态一致。一般情况下主句是将来时的时候，从句要用一般现在时。1.when 当。 。 。的时候Mozart started writing music when he was four years old.(当)莫扎特4岁的时候，开始写音乐作品。2.while 当。 。 。时He visited a lot of places while he was traveling.他在旅途中参观了许多地方。3.as
2、 在。 。 。的同时；一边。 。 。一边。 。 。He smiled as he stood up.他一边站起来一边笑着。4.after 在。 。 。之后He left the classroom after he had finished his homework the other day.前几天做完作业之后回的家。5.before 在。 。 。之前Mr. Brown had worked in a bank for a year before he came here.布朗先生来这之前已经在一家银行里工作一年了。6.as soon as 一。 。 。就。 。 。We began to w
3、ork as soon as we got there.我们一到那就开始工作。I will write to you as soon as I get home.我一到家就给你写信。7.since 自。 。 。以来 到现在表示自过去的一个起点时间到目前(说话时间)为止的一段持续时间。主句一般用现在完成时，从句用一般过去时。Mr Green has taught in that school since he came to China three years ago.自格林先生来中国以来，他就在这所学校教书。(还可以用作介词，本句从句还可以用短语：since three years ago(自
4、三年前以来)表示。)8 till /until都可以作连词，连接时间状语，也可以作介词，与其它词构成介词短语，在句中作状语。They walked till /until it was dark.他们一直走到天黑。Xiao Ming didnt leave home till / until his father came back.小明直到他爸爸回来才离开家。9. by the time 到。 。 。为止 (所在句子的主句应用完成时)By the time he gets there , his father has already gone.他到家的时候，他爸爸已经走了。By the ti
5、me I got to school, the class had already began.我到校时，已经开始上课了。2、when, while 和 as 的区别when 引导的从句的谓语动词可以是延续性的动词，又可以是瞬时动词。并且 when 有时表示 “就在那时”。When she came in, I stopped eating.她进来时，我在吃饭。( 瞬时动词)When I lived in the countryside, I used to carry some water for him.当我在农村时，我常常为他担水。 （延续性的动词）While 引导的从句的谓语动作必须是
6、延续性的，并强调主句和从句的动作同时发生（或者相对应） 。并且 while 有时还可以表示对比。例如：While my wife was reading the newspaper, I was watching TV. (was reading 是延续性的动词，was reading 和 was watching 同时发生)I like playing football while you like playing basketball.我喜欢踢足球，而你喜欢打篮球。 （对比）As 表示“一边一边” ，as 引导的动作是延续性的动作，一般用于主句和从句动作同时发生；as 也可以强调 “一先一
7、后。例如：We always sing as we walk.我们总是边走边唱。 （as 表示“一边一边”）As we was going out, it began to snow.当我们出门时，开始下雪了。（as 强调句中两个动作紧接着先后发生，而不强调开始下雪的特定时间）比较 while, when, as1）as, when 引导短暂性动作的动词。例如：Just as / Just when / When I stopped my car, a man came up to me.我刹车后，有一个人向我走来。2）当从句的动作发生于主句动作之前，只能用 when 引导这个从句，不可用 a
8、s 或 while。例如：When you have finished your work, you may have a rest.干完活后，你可以休息一下。3）从句表示“随时间推移”连词能用 as，不用 when 或 while。例如： As the day went on, the weather got worse. 日子一天天过去，天气越变越坏。三、比较 until 和 till此两个连词意义相同。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。正确使用这两个连词的关键之一就在于判断句中的动词该用肯定
9、式还是否定式。肯定句：I slept until midnight. 我一直睡到半夜时醒了。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。区别：1）until 可用于句首，而 till 通常不用于句首。例如：Until you told me, I had heard nothing of what happened.直到你告诉我以前，出了什么事我一点也不知道。2）until when 疑
10、问句中，until 要放在句首。例如：-Until when are you staying? 你呆到什么时候？- Until next Monday. 呆到下周一。 四、补充内容1. It is since 从。 。 。以来多长时间了(因为 since +从句或名词，表示一段时间)It is five years since we met last time.从我们上次见面已经五年了。2. It is +before(。 。 。才)It was a long time before I went to sleep again.过了很长时间我才睡着。It was an hour before(
11、until) the police arrived.过了一个小时，警察才来。五、附加（可讲可不讲） hardlywhen / before, no soonerthan 相当于 as soon as 之意。主句用过去完成时，从句用一般过去时。He had hardly fallen asleep when he felt a soft touch on his shoulder.他刚要入睡就感到肩膀上被轻轻一触。 由 each time, every time 和 whenever 引导的时间状语从句。Each time he came to Harbin, he would call on me. 他每次来哈尔滨，总是来看我。 由 as long as 和 so long as 引导的时间状语从句。这两个连词表示“有多久就多久”。You can go where you like as long as you get back before dark. 你可以随意到哪里去，只要在天黑以前回来就行。I will fight against these conditions as long as there is a breath in my body! 只要我一息尚存，我就要反对这种境况
