英语时间状语从句的用法及有关说明
一、普通类从属连词
引导时间状语从句的普通类从属连词有when（当……时），while（在……期间），as（当……，一边……一边……），before（在……之前），after（在……之后），since（从……以来），till/until（直到），whenever（无论何时），as soon as（一……就）等。如：
When I went into the classroom, he was reading. 当我走进教室时，他正在看书。
He read a newspaper as he went along. 他边走边看报纸。
We must strike while the iron is hot. 我们必须趁热打铁。
I will tell you after they leave. 于他们走后我再告诉你。
I told him to come back whenever he wants to. 我告诉他什么时候想回来就回来。
I waited till/until she was back. 我一直等到她回来(from www.hxen.com)。
Once time is gone, you will never get it back. 时间一旦失去就再也得不到了
注意：在时间状语从句中，不能用一般将来时、过去将来时态或将来完成时，而要用相应的一般现在时态、一般过去时或现在完成时来代替。如：
I’ll telephone you as soon as I get there. 我一到达那里就打电话给你。
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。
Don’t get off the bus until it has stopped. 等车停稳后才下车。
二、含 time的短语
可引导时间状语从句的 time 短语有every time, each time, (the) next time, (the) last time, by the time, the first time, any time 等。如：
Every time I listen to music, I’ll think of it. 每当我听音乐，我就想起这事。
He didn’t tell me anything the last time I saw him. 上次我见到他时他什么也没告诉我。
Each time she moved her head she let out a moan. 她每转动一下头，就发出一声呻吟。
三、表示“一……就……”
除as soon as外，还有三类：名词型——the moment, the minute, the second, the instant；副词型——immediately, directly, instantly；句式型——no sooner…than…, hardly/scarcely…when…。如：
The moment I saw him I knew that there was no hope. 我一看到他，就知道没有希望了。
I came immediately you called. 你一来电话我就来了。
I had no sooner got home than it began to rain. 我一到家就下起雨来了。
如果hardly, scarcely 或no sooner置于句首，句子必须用倒装结构。如：
Hardly/Scarcely had I got home when it began to rain.
No sooner had I got home than it began to rain.
四、对before从句的理解
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。如：
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。
Before I could get in a word, he measured me. 我还来得及插话，他就给我量好了尺寸。
I’ll water the flowers before it gets dark. 我要趁着天还没黑把花浇好水。
Be a pupil before you become a teacher. 先做学生，后做先生。
Time passed quickly and three months went by before she knew it. 时间过得飞快，她不知不觉就在那里度过了三个月。
I will die before I will betray my country. 我宁可死也不会背叛我的国家。
五、对since从句的理解
1. since从句的谓语动词是终止性动词照字面意思理解。如：
I’ve been feeling down since I lost my job. 自从失去工作后,我的情绪一直处于低潮。
2. since从句谓语动词延续性动词，且为现在完成时时，仍然按字面意思理解。如：
She has never come to see me since I have lived in the city. 自从我住到城里，她就一直不来看我。
3. since从句谓语动词延续性动词，且为一般过去时时，按与字面意思相反的意思理解。如：
I have made great progress since I was ill. 我自病愈以来取得了很大的进步。
4. since前有ever，或从句谓语动词是be且后接表示人成长过程中的某个阶段或年龄的名词、形容词时，仍然按字面意思理解。如：
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。
六、对till/until从句的理解
1. 主句为肯定式，主句谓语动词必须为持续性动词，且该动词所表示的动作或状态一直延续到 until / till 从句所表示的时间为止，可译作“（直）到……”。如：
He waited until/till I returned. 他一直等到我回来。
2. 主句为否定式（包括含 no, nobody, nothing, never, hardly, little 等否定词的肯定句），若主句谓语动词是非持续性动词，则该动词所表示的动作在 until / till 从句表示的时间开始发生。一般先译从句“直到……”，后译主句，not 译成“才”，即“直到……才……”。如：
His mother didn’t leave until/till he was asleep. 直到他睡着了，他母亲才离开。
Nobody can leave until/till the meeting is over. 直到散会才能离开。
3. 主句为否定式，若主句谓语动词是持续性动词，则须根据上下文去理解until/till从句的含义，一般译为“直到……才……”或“没有到……”。如：
He didn’t wait until/till I returned. 他没有等到我回来。
She didn’t sleep until/till I returned. 她直到我回来才睡着。
