高中英语学习中，常遇到状语从句出现省略的情况，尤其是当从句主语与主句主语一致，且从句谓语包括有动词be时，状语从句可省略从句里的主语和部分谓语，具体的情况如下：

1在when,whenever,while,until,as soon as等引导的时间状语从句中,可以省略与主句中主语相同的主语和系动词或助动词。

When (he was) a child he ran wild. 他小的时候很不守规矩。

They were scolded whenever (they were) late for school.每次上学迟到,他们都要挨骂。

While (he was) in prison,he wrote his first novel.他在狱中写出了第一部小说。

As soon as (I am) on board I always feel sick. 我一上船就感到恶心。

2.在“no matter+疑问词”引导的让步状语从句中,可以省略系动词be和重复的主语。

Anyone,no matter who (he is),may point out my shortcoming.不管是什么人,谁向我指出缺点都行。

Anyone who commits a crime must be punished no matter what his position (is).任何犯罪的人都必须受到惩罚,不管他地位多高。

3.在though,as though,as if引导的让步,方式状语从句中，可以省略系动词be和重复的主语。

Though (he is) tall, he is very weak in health. 他虽然长得高,但身体却很弱。

He opened his mouth as if (he was) to speak. 他张开口，好像要说话似的。

4. 在if,unless,once等引导的条件状语从句中。

If (it is) not well organized,the meeting will be a failure.如果组织不好,会议就会失败。

Substances have no tendency to expand unless(they are) heated.除非受热,物质不会有膨胀的倾向。

Once (she was) inside her bedroom,she began to cry. 一走进卧室,她就开始哭。

5.在where,wherever引导的地点状语从句中,可以省略主语和系动词或助动词。

Through long power lines,electricity goes where (it is) needed.电通过输电线输送到需要它的地方去。

6.在than,as引导的比较状语从句中谓语成分一般可以省略。

I know you better than he (does). 我比他更了解你。

He is as quick in answering as his sister (is). 他回答得和他妹妹一样快。

He answers as quickly as his sister (does). 他回答得和他妹妹一样快。

His sister is quicker than he (is). 他妹妹比他敏捷。

Run as fast as you can (run). 你能跑多快就跑多快。

7.结果状语从句so that, so…that, such…that 引导结果状语从句时，有时可省略that。如:

The girls are so close (that) they’re like sisters. 女孩们亲如姐妹。

He was so drunk (that) he could barely stand. 他喝醉了，勉强能站立。

There was such a lot of rain (that) we couldn't go out. 雨那么大，我们没法出去。

8.在“the+比较级,the+比较级”的句型中。

The greater the force of action (is),the greater the force of reaction (is).作用力越大,反作用力也越大。

另外：有些由if构成的省略结构，已属固定短语，如if any, if necessary, if possible, if not, if so。其实他们省略的是 there is, it is 等

There are few, if（ there is ）any, mistakes in that book. 那本书就是有错误也不多。

If （it is )necessary, phone me . 如果必要，可以打电话找我。