(1) 表示“当…时候”或“每当”的时间连词。主要的 when,while, as, whenever。
Don't talk while you're eating.
Vegetables are best when they are fresh.
He came just as I was leaving.
(2) 表示“在……之前(或之后)”的时间连词。主要的有before, after。
Try to finish your work before you leave.
After we have finished tea, we will sit on the grass.
(3) 表示“自从”或“直到”的时间连词。主要的有since, until, till。
She's been playing tennis since she was eight.
Hold on until I fetch help.
Never trouble trouble till trouble troubles you.
(4) 表示“一……就”的时间连词。主要的有as soon as, the moment, the minute, thesecond, theinstant, immediately, directly, instantly, once, no sooner…than,hardly…when等。
I'll let you know as soon as I hear from her.
The moment I have finished I'll give you a call.
I came immediately I heard the news.
Once you begin you must continue.
(5) 表示“上次”、“下次”、“每次”等的时间连词。主要的有every time(每次)，eachtime(每次)，(the) nexttime(下次)，any time(随时)，(the) last time(上次)，thefirst time(第一次)。
I'll tell him about it (the) next time I see him.
We lose a few skin cells every time we wash our hands.
You can call me any time you want to.
注意：every time, each time, any time前不用冠词，(the) next time, (the) last time中的冠词可以省略，而the first time中的冠词通常不能省略。
这类连词主要有if,unless, as [so] long as, in case 等。
Do you mind if I open the window?
Don't come unless I telephone.
As long as you're happy, it doesn't matter what youdo.
In case it rains they will stay at home.
注意：在条件状语从句中，通常要用一般现在时表示将来意义，而不能直接使用将来时态。不过，有时表示条件的 if之后可能用 will，但那不是将来时态, 而是表示意愿或委婉的请求(will为情态动词)。
If you will sit down for a few moments, I'll tell the manager you're here.
主要的有 in order that, so that, in case, for fear等。
He raised his voice so that everyone could hear.
Take your umbrella (just) in case it rains.
She repeated the instructions slowly in order that he should understand.
主要的有so that, so…that, such…that等。
I went to the lecture early so that I got a good seat.
I had so many falls that I was black and blue all over.
He shut the window with such force that the glass broke.
主要的有because, as, since, seeing (that), now (that), considering(that) 等。
He distrusted me because I was new.
As you are sorry, I'll forgive you.
Since we've no money, we can't buy it.
Seeing that he's ill he's unlikely to come.
Now that she has apologized, I am content.
主要的有although,though, even though, even if, while, however,whatever,whoever, whenever, wherever等。
Although they are twins, they look entirely different.
I like her even though she can be annoying.
You won't move that stone, however strong you are.
Whatever we have achieved, we owe to your support.
Whoever you are, you can't pass this way.
Whenever I see him I speak to him.
主要的有as, as if, as though, the way等。
Why didn't you catch the last bus as I told you to?
He bent the iron bar as if it had been made of rubber.
Nobody else loves you the way(=as) I do.
主要的有where, wherever, everywhere, anywhere等。
The church was built where there had once been a Roman temple.
I'll take you anywhere you like.
Everywhere I go, I find the same thing.
She was now happier than she had ever been.
I glanced at my watch. It was earlier than I thought.
He doesn't work as hard as she does.
主要有that, whether, if 等，它们用于引导主语从句、表语从句、宾语从句和同位语从句。其中that 不仅没不充当句子成分，而且没有词义，在句子中只起连接作用；而 if,whether 虽不充当句子成分，但有词义，即表示“是否”。
He replied that he was going by train.
I wonder if it's large enough.
I worry about whether I hurt her feelings.