比较while, when, as
1）as, when 引导短暂性动作的动词。
Just as / Just when / When I stopped my car, a man came up to me.
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as 或 while。
When you have finished your work, you may have a rest.
3）从句表示"随时间推移"连词能用as，不用when 或while。
As the day went on, the weather got worse.
until和till
牛刀小试
我一直睡到半夜时醒了。
I slept until midnight.
公共汽车停稳后再下车。
Don't get off the bus until it has stopped.
直到你教我后，我才会做。
I didn't manage to do it until you had explained how.
区别：1）until可用于句首，而till通常不用于句首。
Until you told me, I had heard nothing of what happened.
2）until when疑问句中，until要放在句首。
---Until when are you staying?
--- Until next Monday.
注意：否定句可用另外两种句式表示。
1） 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.
Not until I began to work did I realize how much time I had wasted.
2）It is not until… that…
It was not until I began to work that I realized how much time I had wasted.
"一…就…"结构
hardly / scarcely…when / before, no sooner…than…和as soon as都可以表示"一…就…"的意思。
I had hardly / scarcely got home when it began to rain.
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 began to rain.
谓语动词
1. 一般现在时He usually goes to work at 7 o’clock every morning.
She has a brother who lives in New York.
考点一：表示永恒的真理，即使出现在过去的语境中，仍用一般现在时。
I learned that the earth goes around the sun when I was in primary school.
考点二：在时间和条件状语从句中，代替一般将来时，常用的引导词有：
时间：when, until, after, before, as soon as, once, the moment / minute / day / year
条件：if, unless, provided
If he accepts the job, he will get more money soon.
考点三：在make sure (certain), see to it, mind, care, matter ＋宾语从句中，从句用一般现在时代替一般将来时。
So long as he works hard, I don’t mind when he finishes the experiment.
考点四：在the more… the more … (越…越…) 句型中, 若主句是一般将来时, 从句通常用一般现在时。
The harder you study, the better results you will get.
2. 现在进行时
We are having English class.
The house is being built these days.
The little boy is always making trouble.
考点一：在时间状语或条件状语从句中表示将来正在进行的动作。
Look out when you are crossing the street.
Don't wake him up if he is still sleeping at 7 tomorrow morning.
考点二：表示在最近按计划或安排要进行的动作（这时多有表示将来的时间状语）。
Mary is leaving on Friday.
3. 现在完成时
考点一：for + 时间段；since + 时间点
They have lived in Beijing for five years.
They have lived in Beijing since 2002.
考点二：常见的不确定的时间状语：lately, recently, just, already, yet, up to now; till now; so far, these days
Has it stopped raining yet?
考点三：在表示“最近几世纪/年/月以来……”时间状语中，谓语动词用现在完成时。in the past few years/months/weeks/days, over the past few years, during the last three months, for the last few centuries, through centuries, throughout history 等
In the past 30 years China has made great advances in socialist construction.
考点四：表示“第几次做某事，”或在 “It is the best (worst, most interesting ) +名词＋that” 后面用现在完成时。
This is my first time that I have visited China.
This is the most interesting film I have ever seen.
That is the only book that he has written.
4．一般过去时
常与明确的过去时间状语连用，如：yesterday, last week, in 1972, at that time, once, during the war, before, a few days ago, when。
考点一：used to + do 表示过去经常但现在已不再维持的习惯动作。to为不定式符号，后接动词原形。
比较：be / become / get used to + doing 表示习惯于
He used to smoke a lot.
He has got used to getting up early.
考点二：在时间和条件状语从句中，代替过去将来时。
He promised to buy me a computer if he got a raise
5. 过去进行时
What were you doing at nine last night?
The boy was doing his homework when his father came back from work.
He was taking a walk leisurely by the lake when he heard someone shouted for help.
6. 过去完成时
从来不孤立使用。
There had been 25 parks in our city up till 2000.
By the end of last term we had finished the book.
They finished earlier than we had expected.
考点一：用于hardly/scarcely...when; no sooner ...than 句型中，主句用过去完成时，从句用一般过去时。
I had hardly woken up when my baby began to cry.
No sooner had I arrived home than the telephone rang.
考点二：表示“第几次做某事”或有最高级修饰时，主句用过去时，从句用过去完成时。
That was the second time that she had seen her grandfather.
That was the best film that I had（ever）seen.
考点三：动词hope, expect, think, intend, mean, want, suppose, plan 用过去完成时，表示未实现的愿望、打算和意图。
I had hoped that I could do the job.
I had intended to see you but I was too busy.
7. 一般将来时
常和tomorrow, next year, in 2008等表示将来的时间状语连用，其表现形式多达5种。
考点一：一般将来时总是用在一些时间状语从句或条件状语从句的主句中。
We will begin our class as soon as the teacher comes.
考点二：某些表示短暂性动作的动词如arrive, come, go, leave, start等，用现在进行时形式表示将来。
I am leaving for Beijing tomorrow.
考点三：“祈使句 + and / or + 句子”，这种结构中and后面的句子谓语用一般将来时。
Use your head and you will find a way.
考点四：“be going to + 动词原形”，表示打算要做的事或可能要发生的事。
“be about to + 动词原形”表示按照预定计划或打算准备着手进行的动作。
“be to + 动词原形”表示必须、必然或计划将要做的事。
They are to be married in May.
8. 将来进行时
I’ll be doing my homework this time tomorrow.
The President will be meeting the foreign delegation at the airport.
9. 将来完成时
考点一：常用的时间状语一般用by + 将来时间，如：by the end of this year, by 8 o’clock this evening, by March next year以及由by the time…, before或when等引导的从句。
By the end of next month, he will have traveled 1000 miles on foot.
By the time you reach the station, the train will have left.
By next Tuesday, I will have got ready for the exams.
考点二：在时间和条件状语从句中，将来完成时则由现在完成时表示。
The children will do their homework the moment they have arrived back from school. (环球网校资料,如需转载请注明出处)