When you apply for a job, you must present your credentials.
We were having breakfast as she was combing her hair.
While the teacher paraphrased the text in English, the students listened attentively and took notes.
It was three days before I came back.
As soon as we got home, the telephone rang.
Great changes have taken place since you left.
Donald will remain in college until(till) he finishes his Ph.D course.
2. 地点状语从句
He said he was happy where he was.
3. 原因状语从句
I didn’t go abrord with her because I couldn’t afford it.
As it is snowing, we shall not climb the mountain.
Since traveling by air is much faster,they decided to take a plane.
Now(that) you have passed your test you can drive on your own.
4. 目的状语从句
The expert spoke slowly in order that everyone should understand.
Speak clearly so that they may understand you.
Take your umbrella in case it rains.
5. 结果状语从句
Linda phoned me in on arrival so that I know she was safe and sound.
She spoke so fast that nobody could catch what she was saying.
The professor told us such a funny story that all the students laughed．
6. 条件状语从句
We’ll start our project if the president agrees.
7. 让步状语从句
Although they have been talking for a long time, he cannot make her believe him.
8. 方式状语从句
I did just as you told me.
9. 比较状语从句
We were as fortunate as them (they were)
主要引导词用法
as 用法
时间状语从句
as表示“当……的时候”,引导时间状语从句,多强调主句和从句中的动作或状态同时发生,从句可放在主句前,也可放在主句后。例如：
As I waited at the stop, I heard a big noise. 当我在车站等车的时候,我听到一个很大的声响。 She rose up as he entered. 当他进来时,她站了起来。
原因状语从句
as表示“因为”、“由于”,引导原因状语从句,其语气不如because强,通常为附加说明的理由,且是已知晓的原因,主句与从句没有逻辑上的因果关系。例如：
As she was not well, I went there alone. 因为她身体不好,所以我独自到那里去了。
As he is a tailor, he knows what to do with this material. 由于他是个裁缝,他知道怎样利用这块布料。
让步状语从句
as表示“虽然……但是……”,引导让步状语从句,从句通常用倒装语序,把从句的表语、状语或动词原形放在as前面,可以用though替代。例如：
Child as he is, he knows a lot. 虽然他是个孩子,但他知道的东西很多。
Hard as it was raining, they went on working in the field. 虽然天下大雨,但他们继续在田地里干活。
方式状语从句
as表示“按照”、“依照”、“像”,引导方式状语从句,从句置于主句之后。例如：
You should do as the teacher tells you.你应当依照老师所说的去做。
The absence of air also explains why the stars do not seem to twinkle in space as they do from the earth. 空气的不存在,也说明了为什么在空中星星看来并不闪烁,而不像从地球上看的那样。
比较状语从句
as表示“像……一样”,引导比较状语从句,对主句和从句的动作或状态加以比较,说明它们之间有相似之处,在从句中常省略与主句相同的部分。例如：
He doesn't work as hard as I (do). 他不像我工作那样努力。
I hope the necklace was as good as the one you lent me.我希望我挂项链同你借给我的一样好。
since用法
时间状语从句
He has studied very hard since he came to our school.
We have been missing them since they left here.
原因状语从句
Since you are not interested, I won't tell you about it.
no matter + 疑问词和“疑问词-ever
都可以引导让步状语从句，表示”无论······；不管······都······“
No matter who you are, you must obey the law.
Whoever you are, you must obey the law.
No matter when Lucy comes, she says the same words.
Whenever Lucy comes, she says the same words.
No matter how difficult it is, we will try to overcome it.
However difficult it is, we will try to overcome it.
