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。
3. 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。
4. 在than,as引导的比较状语从句中。
Ｓhe works better than Ｉ (works). 她工作做得比我好。
I’d rather play football than (I’d rather) go swimming. 与其去游泳我还不如去踢足球。
Run as fast as you can (run). 你能跑多快就跑多快。
5. 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。
6. 在whatever,however引导的让步状语从句中,可以省略系动词。
He was determined to carry out the plan,whatever the cost (was).他决心执行计划,不管代价如何。
However difficult the task (may be),we must finish it on time.不管这任务有多难,我们都必须按时完成。
7. 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。
8. 在though,as though,as if引导的让步状语从句中。
Though (he is) tall, he is very weak in health. 他虽然长得高,但身体却很弱。
He went quickly out of the room as if (he was) in a hurry.他很快走出房间,好像很匆忙似的。
