1. 在when,whenever,while,until,as soon as等引導的時間狀語從句中,可以省略與主句中主語相同的主語和系動詞或助動詞。

When (he was) a child he ran wild. 他小的時候很不守規矩。

They were scolded whenever (they were) late for school.每次上學遲到,他們都要挨罵。

While (he was) in prison,he wrote his first novel.他在獄中寫出了第一部小說。

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

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2. 在if,unless,once等引導的條件狀語從句中。

If (it is) not well organized,the meeting will be a failure.如果組織不好,會議就會失敗。

Substances have no tendency to expand unless(they are) heated.除非受熱,物質不會有膨脹的傾向。

Once (she was) inside her bedroom,she began to cry. 一走進臥室,她就開始哭。

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3. 在where,wherever引導的地點狀語從句中,可以省略主語和系動詞或助動詞。

Through long power lines,electricity goes where (it is) needed.電通過輸電線輸送到需要它的地方去。

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4. 在than,as引導的比較狀語從句中。

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. 與其去游泳我還不如去踢足球。

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

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5. 在“the+比較級,the+比較級”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。

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6. 在whatever,however引導的讓步狀語從句中,可以省略系動詞。

He was determined to carry out the plan,whatever the cost (was).他決心執行計劃,不管代價如何。

However difficult the task (may be),we must finish it on time.不管這任務有多難,我們都必須按時完成。

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7. 在“no matter+疑問詞”引導的讓步狀語從句中,可以省略系動詞be和重復的主語。

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

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

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8. 在though,as though,as if引導的讓步狀語從句中。

Though (he is) tall, he is very weak in health. 他雖然長得高,但身體卻很弱。

He went quickly out of the room as if (he was) in a hurry.他很快走出房間,好像很匆忙似的。