(一)时间状语从句

表示时间的状语从句可由when, as, while, whenever, after, before, till (until), since, once, as soon as (或the moment ), by the time, no sooner than, hardly (scarcely) when, every time等引导。

e.g. When I came into the office, the teachers were having a meeting.

He started as soon as he received the news.

Once you see him, you will never forget him.

No sooner had I gone to bed than I went to sleep.

(二)原因状语从句

原因状语从句是表示原因或理由的，引导这类从句的最常用的连词是because, since, as , now that(既然)等，for 表示因果关系时(它引导的不是从句)为并列连词，语气不如because强。

e.g. He is disappointed because he didn't get the position.

As it is raining, I will not go out.

Now that you mention it, I do remember.

(三)地点状语从句

引导地点状语从句的连词是where 和wherever等。

e.g. Sit wherever you like.

Make a mark where you have a question.