高中语法专练：i. 主语从句

i. 主语从句

1. that从句作主语通常用it作形式主语，常见的这样的主语从句结构有：

1）It + be +名词（a pity/fact/problem/shame/surprise/no wonder等）+that从句

It is a pity that we missed the interesting film.

很遗憾我们错过了那场有趣的电影。

It is an honor that I am often invited to dinner.

真荣幸我经常被邀请去赴宴。

2）It+be+形容词（natural/certain/clear/obvious/evident/necessary/true/likely/probable/possible/strange/important等）+that从句

It is likely that it will snow this afternoon.

很有可能今天下午要下雪。

注意： 当形容词是important/natural/necessary/strange/essential/surprising等时，从句谓语用（should）+动词原形

It is necessary that we (should) buy a new car.

我们很有必要买辆车。

3）It+不及物动词（seems/turns out/happens/appears/follows/occurs to sb.）+that从句

It seems that our sports meeting will have to be put off because of the weather.

我们的运动会似乎因天气原因将不得不被推迟。

It occurred to her that she had forgotten to lock the door.

她突然想起忘记锁门了。

4）It+be+过去分词（known/said/reported/believed/announced/accepted/found/claimed/declared/thought/hoped/suggested）+that从句

It is said that they have succeeded in passing the college entrance exam.

据说他们成功地通过了大学入学考试。

It has been proved that light runs much faster than sound.

已证实光速比声速快得多。

注意： 当过去分词是suggested/demanded/required/commanded/recommended/ordered等时，从句谓语用 (should) +动词原形

It is required that every one (should) obey the traffic rules.

要求每一个人都应该遵守交通规则。

注意：

1）在正式文体中，为了强调that从句，可将that从句置于句首。

That China is in the east of Asia is well known to all of us.

中国位于亚洲东部这是众所周知的。

That the driver could not control his car was obvious.

很明显司机不能控制他的车了。

2）在疑问句中只能用形式主语it结构。

Is it true that he would take the risk?

他是真的要冒险吗？

Isn't it amazing that so many passengers were unhurt in the accident?

那么多旅客在事故中没有受伤难道不令人吃惊吗？

2. wh-从句

1）表示“是否”意义时，只能用whether不能用if引导主语从句。

Whether a new product sells well depends on its quality and price.

一种新产品是否畅销取决于它的质量和价格。

2）it经常用来作形式主语，而把wh-从句放句尾，常见的结构为：

It is not yet clear wh- ....

It is strange wh- ....

It is uncertain wh- ....

It it not known wh- ....

It depends on ... wh- ....

It depends on its quality and price whether a new product sells well.

一种新产品是否畅销取决于它的质量和价格。

It isn't clear whether she would come.

她是否愿意来还不清楚。

3）wh-从句经常可以放句首。

What he said didn't refer to me.

他所说的并非指我。

Who should be chosen to do the job hasn't been decided.

谁应该被选中做这件工作还没决定。

What he needs is more experience.

他所需要的是更多的经验。

Where we will go for our holiday hasn't been decided.

我们去哪儿度假还没有决定。

专项练习

1. _______ she couldn't understand was _______ fewer students showed interest in her lessons.

A. What; why

B. That; what

C. What; because

D. Why; that

2. It worried her a bit _______ her hair was turning gray.

A. while

B. that

C. if

D. for

3. It is pretty well understood _______ controls the flow of carbon dioxide in and out the atmosphere today.

A. that

B. when

C. what

D. how

4. _______ man first made use of electricity is not exactly known.

A. When

B. If

C. That

D. What

5. _______ we will have a meeting hasn't been decided yet.

A. If

B. That

C. What

D. Whether

6. _______ we are saying is more than _______ we will do.

A. That; that

B. What; what

C. Whatever; that

D. As; as

7. _______ leaves last turns off the light.

A. Who

B. Whoever

C. No matter who

D. Whomever

8. _______ wins the prize may get the car.

A. Who

B. Whom

C. Whomever

D. Whoever

9. _______ a pity that I didn't see you last week.

A. That's

B. What's

C. It's

D. There's

10. _______ she will come is certain.

A. That

B. What

C. /

D. Whether

11. _______ we go swimming every day _______ us a lot of good.

A. If; do

B. That; do

C. That; does

D. If; does

12. _______ has questions can ask the teacher after class.

A. Who

B. Whoever

C. Anybody

D. One

13. _______ is one of the most useful and fascinating divisions of human knowledge is widely accepted.

A. Where chemistry

B. That chemistry

C. What chemistry

D. Chemistry

14. It's known to us _______ chewing gum helps prevent tooth decay.

A. why

B. that

C. whether

D. how

15. Does _______ matter if he can't finish the job on time?

A. this

B. that

C. he

D. it

16. _______ water can be used to _______ electricity is true.

A. That; producing

B. That; produce

C. This; producing

D. This; produces

17. After Yang Liwei succeeded in circling the earth, _______ our astronauts desire to do is walk in space.

A. where

B. what

C. that

D. how

18. It is doubtful _______ he knows it or not.

A. that

B. if

C. what

D. whether

19. _______ caused the accident is still a complete mystery.

A. What

B. That

C. How

D. Where

20. _______ we will have a meeting hasn't been decided yet.

A. If

B. That

C. What

D. Whether

21. It doesn't matter _______ will take charge of the work.

A. who

B. whoever

C. whom

D. whomever

22. _______ is worth doing at all is worth doing well.

A. That

B. Which

C. Whatever

D. It

23. _______ land ownership in some countries is unfair _______ obvious.

A. What; is

B. Whether; are

C. That; is

D. If; is

24. _______ some mammals came to live in the sea is not known.

A. That

B. Since

C. Although

D. How

25. _______ troubles me is _______ my son can finish all _______ he is expected to do.

A. That; whether; /

B. What; if; that

C. That; if; what

D. What; whether; /

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