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.
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.
e.g. Sit wherever you like.
Make a mark where you have a question.
引导目的状语从句最常用的词组）是so， so that从句谓语常有情态动词）， in order that， in case以防，以免）等。
e.g. Speak clearly， so that they may understand you.
She has bought the book in order that she could follow the TV lessons.
He left early in case he should miss the train.
结果状语从句是表示事态结果的从句，通常主句是原因，从句是结果。由so that从句谓语一般没有情态动词）， so ;; that， such ;; that等引导。