UNIT 4 Astronomy: the science of the stars
Teaching Goals:
To get Ss to have the knowledge of this grammar point: noun clauses as
the subject
Teaching important and difficult points :
How to make the students use the sentences correctly.
Teaching aid
A computer, a projector
Teaching Procedures:
Step 1. Grammar
导入：由连词 that 引导的主语从句，在大多数情况下会放到句子的后面，而用
代词 it 作形式主语。如：
It’s necessary for the young to master two foreign language.
It’s a waste of time talking to her any more.
It’s a pity that you missed the exciting football match.
这三个句子分别由动词不定式，动名词和从句充当真正的主语，it 做形式主语
It 作为形式主语的用法
当不定式、动名词、从句等用作句子主语时，为保持句子平衡，通常把真正的主
语放在句末，而在句首使用形式主语 it.
一 常见用 it 作形式主语的复合句结构
①It +be +adj.+（for sb.）to do sth.
此处 adj. 通常为描述事件的形容词：easy，difficult，hard，necessary，
impossible， important，natural, likely，obvious，useful，useless，
dangerous…做某事是…
It’s necessary for us to master a foreign language.
②It +be+ adj.+ of sb. to do sth
此处 adj. 通常为描述人的形容词：kind，nice，rude，cruel，careless，foolish，
stupid，wise，crazy…某人做某事，某人是…
eg. It’s foolish of you to drive a car after drinking.
It’s very kind of you to help me with my English.
③It + be +名词词组+动词不定式
eg. It is not a good habit to stay up too late.
常见句型：
It takes/took sb. some time/money to do sth.
二、代替动名词作形式主语
It is no good crying over spilt milk
覆水难收
It is no use casting pearls before swine .
不要明珠暗投，对牛弹琴
构成如下结构：
It is +no use/no good/not any good/not any use…+ doing sth.
①It + be + 名词词组 + 主语从句
这类名词有：a fact, a pity, a shame, an honour，a question，a surprise，
common knowledge…
eg.It’s common knowledge that people cann’t live without water .
②It + 不及物动词 + that（as if）-从句
这类不及物动词有：look，seem，appear，happen，occur
eg.It seems that he does not tell the truth.
③It + be +adj.+that-从句
It is time +that sb. +v-ed/ should do
Eg. It’s time that you went to bed
It’s time that you should go to bed.
It’s necessary/ impossible/ important/ natural that sb. (should) do
Eg. It’s important that we (should) keep the balance of nature.
③It + be +adj.+that-从句
It is time +that sb. +v-ed/ should do
Eg. It’s time that you went to bed
It’s time that you should go to bed.
It’s necessary/ impossible/ important/ natural that sb. (should) do
Eg. It’s important that we (should) keep the balance of nature.
④It + be +-ed（过去分词）+ that-从句
It is said that… 据说…
It is reported that… 据报道…
It is supposed that… 据推测…
It is hoped that… 希望…
It is well known that… 众所周知…
It is generally considered that…普遍认为…
It is suggested that… 有人建议…
Step2.Exercise
Step3.Summary
It 做形式主语的句型：
It +be +adj.+（for sb.）to do sth.
It +be+ adj.+ of sb. to do sth
It + be +名词词组+动词不定式
It is +no use/no good/not any good/not any use…+ doing sth.
It + be + 名词词组 + 主语从句
It + 不及物动词 + that（as if）-从句
It + be +-ed（过去分词）+ that-从句
Please remember them .Practise makes perfect.That is all for this.
Step 4. Homework
Ask Ss to learn the rules of noun clauses as the subject by heart.
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