人教高中英语必修3 Unit 4 Astronomy: the science of the starsGrammar (共33张PPT)

(共33张PPT)
Rewrite the following sentences with noun clauses as the subject.
1. His discovery has not yet been proved.


2. Do the other astronomers accept his
ideas? It remains a question.
What has not yet been proved is his discovery.


Whether the other astronomers accepts his ideas remains a question.
3. The first appearance of life on earth is
still a mystery to scientists.


4. Why is the earth becoming warmer? It
is an important topic for research.
How life first appeared on earth is still a mystery to scientists.


Why the earth is becoming warmer is an important topic for research.
5. Stephen Hawking at 65 experienced zero gravity during a flight. It amazed everybody.



6. Pluto is no longer considered a planet in
our solar system. What a surprise!
It amazed everybody that Stephen Hawking at 65 experienced zero gravity during a flight.


It is a surprise that Pluto is no longer considered a planet in our solar system.
主语从句在复合句中作句子的主语。引导主语从句的词有从属连词that, whether, if；连接代词who, whoever, whom, what, whatever, whose, which；连接副词when, where, how, why等。
【例句呈现】
观察下列例句，指出其中所包含的主语 从句及引导词:
1. What is needed for a long trip is careful preparation.
该句中主语从句是 __________________ _________，引导词为 _____。
What is needed for a
what
long trip
2. That Jay Zhou will come to my city excites everybody.
该句中主语从句是 _________________
______________，引导词为_____。
3. Whether we will travel abroad or not has not been decided.
该句中主语从句是 _________________
__________________，引导词为 _________。
That Jay Zhou will
Whether we will
come to my city
that
travel abroad or not
whether
4. Whoever knows the secret mustn’t tell others.
该句中主语从句是__________________
______，引导词为________。
5. It remains a puzzle why dinosaurs died out suddenly long time ago.
该句中主语从句是_________________
_______________________，引导词为 _____。
Whoever knows the
whoever
why dinosaurs died
why
secret
out suddenly long time ago
【观察总结】
通过分析上面例句，同学们可能会发现上面第5句中的主语从句似乎比较隐蔽。其实，这也是主语从句的一种呈现方式，即：当一个句子主语过长时，可以用it作形式主语，而把真正的主语或主语从句后移至句子末尾，以保持句子的平衡。注意观察下列例句中的划线部分：
It is not clear how the accident happened.
It is not hard to understand why he did so at that time.
It is a pity that you should have made such a careless mistake.
It is reported that more than thirty deaths were caused in the accident.
不难看出，虽然上面例句中都用it作形式主语，但句子结构却不尽相同。现将常见的由it作形式主语的句型总 结如下：
1. It is + n. + that从句
2. It is + adj. + that从句，常见此类形容 词有：important, necessary, clear, certain, natural, strange, obvious, likely, impossible, possible等。
3. It+特殊动词+that 从句
It seems / appears ... that ...
似乎……
It happened (to sb.) that ...
（某人）碰巧……
4. It + be + 过去分词 + 主语从句
It is said / reported / believed / suggested / known / proved that ...
【要点精讲】
1. what与that引导主语从句
观察下列例句，试着翻译例句并总结 其规律。
(1) What you lack is self-confidence.
译为：_________________________
你所缺乏的是自信。
(2) That more and more students are admitted into universities is true.
译为：___________________________
___________________________
(3) What is needed for the program is more wisdom.
译为：_____________________________
这个项目所需要的是更多的智慧。
越来越多的学生将被大学录取的消息是真实的。
从上面例句可以看出，that引导主语从句时，在句中具有“两不”原则：
一、不作句子成分；
二、没有实际意义。
当它引导的主语从句置于句首时，that不能省略；如果用it作形式主语，而把主语从句放在句末时， that可以省略。
而what引导的从句则恰恰相反，what在从句中的作用为：
一、作句子成分；
二、除了起到引导从句的作用外还
要承担具体的意义。
【巩固练习】
用what或that填空。
(1) _____ he told us this morning was just a lie.
(2) _____ is important to us is enough time.
(3) It worries my mom _____ she is beginning to get a little fat.
(4) _____ we can’t get seems better than _____ we have.
What
What
that
What
what
2. whether与if引导主语从句
如果主语从句置于句首，不能用if引导，此时，需用whether。但如果用it作形式主语，而把主语从句放在句末时，也可以用if引导。
【巩固练习】
用whether或if填空。
(1) It doesn’t matter ___________ he will come or not.
(2) ________ we’ll go camping tomorrow depends on the weather.
(3) It was doubtful ___________ Tom really saw Sharon.
(4) ________ Tom really saw Sharon was doubtful.
whether / if
Whether
whether / if
Whether
3. 其它引导词
连接代词who, which, whom, whose有各自的具体意义，起连接作用，同时在从句中充当主语、宾语、表语、定语等；whoever, whatever, whichever在意义上更为强调，常译为“无论……”；连接副词when, where, why, how等也有各自的意义，起连接作用，并在从句中作状语。
【常见错误展示】
下列各句均有一处错误，请改正并分析错误的原因。
1. Light travels faster than sound is common knowledge.
That
that虽无词义但引导主语从句位于句首时不能省略。
if, whether都可表示“是否”, 但if不能引导位于主句之前的主语从句，它可以引导位于主句之后带有形式主语it的主语从句。
2. If she’s coming or not doesn’t matter much.
Whether
3. That the professor said is of great importance.


4. Where will the trees be planted has
not been decided.
What
that引导主语从句时无词义。What the professor said表示“教授所说的”。
将will置于trees之后。主语从句要用陈述句语序。
5. No matter who breaks the rule will be punished.


6. When and where the meeting will be held still remain a question.
引导让步状语从句时二者可互换，但引导名词性从句时只能用whoever。
Whoever
主语从句表示单一概念时，谓语要用单数形式。
remains
7. What were your problems a year ago has now become mine.


8. It was requested that everyone
made a speech at the meeting.
has要改为have。主语从句表示复数概念时，谓语要用复数形式。
have
在“It is requested / ordered / suggested + that从句”中，从句要用虚拟语气，即谓语用“should + 动词原形”，should可省略。
(should) make
从A、B、C、D四个选项中，选出可 以填入空白处的最佳选项。
1. It is still under discussion _____ the old bus station should be replaced with a modern hotel or not.

A. whether B. when C. which D. where
2. The villagers have already known _____ we’ll do is to rebuild the bridge.
A. this B. that C. what D. which
3. _____ some people regard as a drawback is seen as a plus by many others.
A. Whether B. What C. That D. How
4. It never occurred to me _____ you could succeed in persuading him to change his mind.
A. which B. what C. that D. if
5. It is uncertain _____ side effect the medicine will bring about, although about two thousand patients have taken it.
A. that B. what C. how D. whether
Finish Using Structures on Page 64 of the Workbook.