The science of the stars
2）it引導的強調句與it作形式主語的復合句不可混淆。it引導的強調句是用來對句中某一成分加以強調，其結構為：“it is（或was）+強調部分+that（或who）…”強調句去掉it is（或was）…that（或who）…框架后，剩余部分為一個完整的句子。
it was i that(who) met mary in the street yesterday.是我昨天在街上遇見了瑪麗。(強調主語)
3）常見的用it作形式主語的復合句結構：
*it is+形容詞（nec essar y，strange，important，wonderful，possible，likely，等）+that從句，從句中常用虛擬語氣。
it’s necessary that he write something in english.他用英語寫點東西是必要的。
it’s strange that she did not go to school yesterday.奇怪的是她昨天沒去上學。
*it is+名詞（a fact，a pity ，no wonder，good news，等）+that從句
it's a pity that she should have said so.真遺憾她竟然會這么說。
*it is+過去分詞（said，reported，decided，unknown等）+that從句
its said that our english teacher will go abroad next week.據說我們英語老師下周要去出國。
*it +不及物動詞（ seems，appears，happens， matters等）+that從句
it seems that she is in great need of help.看來她急幫忙。
4）主語為從句時，一般要用單數謂語動詞形式；但如果引導的從句作主語、代表復數概念（常可從表語上看出）時，謂語動詞則常用復數形式：
what we need is water. 我們需要的是水。
what we need are useful books. 我們需要的是有用的書。
三、由連接代詞或連接副詞（或if, whether）引導的主語從句。
when they will come hasn't been made public.他們什么時候回來還沒有宣布。
whether i’ll attend the meeting hasn’t been decided.=it hasn’t been decided whether(if) i’ll attend the meeting.我是否參加會議還未決定。
4.closing down by doing an quiz
1. noun clause practice quiz
1) i had an accident and took my car to the garage. my husband asked me where ________.
a. is my car b. my car was c. my car is d. was my car
2) is it true all of the computers will shut down in the year ? _______ is unbelievable!
a. that all the computers could shut down b. all computers could shut down
c. it is that all computers could shut down d. shutting down of all computers
3) is it true __________ people are saying about y2k?
a . that what b. that c. whether or not d. what
4) _______________ an old "date" chip is im portant.
a. a computer has b. if a compute r have
c. whether or not a computer has d. has a computer
5) what are you going to do with your old computer? nothing! _________ is too expensive.
a. that i want to do b. what i want to do c. that what i want to do d. if what i want to do
keys: b a d c b