知识点名:状语从句(时间、原因)

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讲义:

一、时间状语从句

1. when与while

while引导时间状语从句时,表示“当(在)……时”,强调during that time,while从句中常用延续性动词或表状态的词。当两个延续性动作同时发生时,用while。while引导的从句与主句之间可构成对比。

例:While I was playing the piano, she was dancing.

2. when表示“当(在)……时候”时,when相当于at that time或during that time,既指时间点,也可指一段时间,引导的从句可用瞬间动词,也可用延续性动词(相当于while) ;与主句所表达的动作有先后,也可同时进行。

例:Jim was reading when the teacher came in.

3. until“直到”,表示某行为一直持续到某一时间,用在肯定句中,句子的谓语动词必须是延续性的。not...until“直到……才”,表示直到某一时间,某一行为才发生,之前该行为并没有发生,用在否定句中,主句中的谓语可以是延续性动词也可以是短暂性动词。

例:I didn't go to bed until my father came back.

I studied English until 9 o'clock last night.

4. 由as soon as (=the moment)引导的时间状语从句表示“一……就”。

二、原因状语从句

1. 引导原因状语从句的连词

原因状语从句一般由从属连词because, as, since, now that引导。

2. because, as, since和now that的区别:

because“因为”,表示直接的原因,语气最强。why提问的句子,必须用because回答。because从句常放在主句之后。because 不能与so连用。because后跟从句,because of后跟名词或名词短语。

例:I did it because he told me to.

as“因为”,语气较弱,一般放在主句前,中间用逗号隔开,表示的是明显的原因。

例:Enjoy the first hour of the day. This is important as it sets the mood for the rest of the day.

since/ now that “既然”,一般放在主句前,中间用逗号隔开,表示的是明显的原因或众所周知的事实。

例:We thought that, since we were in the area, we'd stop by and see them.

3. for 引导的并列句与原因状语从句的辨析

并列连词for意为“因为”,引导的不是从句,而是并列分句,只能放在主句之后,不能放在句首,常用逗号把它和前面的分句隔开,对主句补充说明理由或推断原因。

例:I believed her, for surely she would not lie to me.