中考英语知识点：知识扩展
 

1. It is since从…以来多长时间了(因为since +从句或名词，表示一段时间)

It is five years since we met last time.从我们上次见面已经五年了。
 

2. It is +before…(…才)

It was a long time before I went to sleep again.

过了很长时间我才睡着。

It was an hour before(=until) the police arrived.

过了一个小时，警察才来。
 

(中考英语状语从句)
 

3. 由as soon as, immediately, directly, instantly, the moment, the instant, the minute, 等引导的时间状语从句。这些连词都表示"一…就"。例如:

I will go there directly I have finished my breakfast. 吃完早饭，我立即到那里去。

The moment I heard the news, I hastened to the spot.我一听到消息，马上赶到了出事地点。

As soon as I reach Canada, I will ring you up. 我一到加拿大，就给你来电话。
 

4.【注意】hardly(scarcely, rarely)…when / before, no sooner…than相当于as soon as之意。

主句用过去完成时，从句用一般过去时。当hardly, scarcely, rarely和no sooner位于句首时，主句应用倒装语序。例如:

He had no sooner arrived home than he was asked to start on another journey. 他刚到家，就被邀请开始另一旅程。

No sooner had the sun shown itself above the horizon than he got out of bed to commence work.太阳刚从地平线上升起，他就起床劳动去了。

Hardly had I sat down when he stepped in.我刚坐下，他就进来了。

He had hardly fallen asleep when he felt a soft touch on his shoulder.这个阿拉伯人刚要入睡就感到肩膀上被轻轻一触。
 

5.by the time引导的时间状语从句：注意时态的变化:在一般情况下，如果从句的谓语动词用一般过去时，主句的谓语动词用过去完成时;如果从句的谓语动词用一般现在时，主句的谓语动词用将来完成时。

By the time you came back, I had finished this book.到你回来时，我已经写完这本书了。

By the time you come here tomorrow, I will have finished this work. 你明天来这儿的时候，我将已经完成此工作了。
 

6. 由as long as和so long as引导的时间状语从句。这两个连词表示"有多久……就多久"。例如:

You can go where you like as long as you get back before dark. 你可以随意到哪里去，只要在天黑以前回来就行。

I will fight against these conditions as long as there is a breath in my body! 只要我一息尚存，我就要反对这种境况。