连词主要有: when as while before after until as soon as since等。
( 1)区别 when, as, while的用法
① when"当......时候"引导的时间状语从句,其动词既可以是延续性动作的动词,也可以是瞬间性动作的动词,如:
_________ the students heard the teacher's footsteps, they all stopped talking.
当学生们听到老师的脚步声时,他们都停止了讲话。(从句动作发生在前)
② as"当.......时候"或"一边一边"引导的时间状语从句其动词的动作是延续性的,而且侧重表示主句和从句的动作并相发生:
We were having breakfast__________ she was combing her hair.
她梳头时我们在吃早饭。
③ while表示"在某一段时间里"或"在……期间",其所引导的从句的动作是延续性的,并侧重表示和主句的动作同时发生。如:
I can learn________ I work.
我可以边工作边学习。
用 when, as, while填空:
________ you came in, I was talking with a few boys.
It started to rain__________ we were playing outdoors.
They talked_________ they walked down the river.
__________ it was raining, the students were playing basketball.
Her brother watched TV__________ he ate supper.
( 4) before引导的时间状语从句,指时间上的"在……之前"
I'll be back_____________.
你离开之前我就会回来。
( 5) as soon as表示"一……就",做题要注意主将从现
As soon as we__________ (get) there, he___________ (tell) us the news.
我们一到那,他就会告诉我们那个消息。
( 7) since引导的时间状语从句,从句的谓语动词通常为一般过去时,主句的谓语动词通常为现在完成时
We__________ never__________ (meet) since we___________ (graduate) from the college.
大学毕业后我们就再没见过面。
( 8) till/ until引导的时间状语从句 till和 until同义,作"直到……时(为止)"解, till多用于非正式文体, until多用于句首; not… until通常与 after进行转换。如:
I won't go with you until (till) I finished my homework. =_________
等我做完作业我才和你一起去。