I.要点
1、it的用法
(1)用作人称代词，代替前文提到的无生命的事物，动植物、婴儿及指示代词this， that，如，
I have a
new pen. It is beautiful.
The Browns
have a new baby. It's cute.
(2)用来表示时间、天气、距离等，如，
It's
twelve o'clock now.
It's fine
today.
(3)用作引导词，代替由不定式，ing形式或从句表示的真正的主语或宾语，如，
It's no
good telling him that.
It's
necessary for you to do so.
(4)用在强调结构中，构成强调句式：It is/was +被强调部分+that/who/whom +句子其余部分，可强调除谓语以外的句子其他成分，如，
It was
this morning that I saw him in the street.
It was I
who saw him in the street this morning.
It was in
the street that I saw him this morning.
It was him
whom I saw in the street this morning.
2、there be句型
英语表示某时某处或某物时，常用there be句型，这是一种倒装结构，如，
There are
a lot of students playing on the ground.
There is
going to be a test this afternoon.
当主语有两个或两个以上时，动词be常和最近的那个主语取得一致，如，
There is a
pen and three pencils in the pencil-box.
There
isn't a desk， a bench and three chairs in the room.
There are
lots of people like it， aren't there？
there be句型，谓语动词除be之外，还可用其他表示存在，位置移动等意义的不及物动词或词组，如exist， stand， lie， enter， come， happen to be，
appear to be等，如，
There
stands a house at the foot of the hill.
there be句型表示“存在”而have表“有”、“拥有”，所以there be中be不能换成have，但当have表示事物的特征时，可用“主语+have”结构替换there be 句型，如：
There are
five doors in the house.
The house
has five doors.
there be 的其它句型：
1、There must be a meeting in the office.
2、There have been great changes since 1979.
3、There being no bus， we had to walk home.
I.例题
例1____
that he went to sleep.
A It was
until midnight B That was until midnight
C It was
not until midnight D That was not until midnight
解析：该题答案为C。强调until结构时，要将否定词not移到until前。又如：He didn't leave until twelve 改为It was not
until twelve that he left.
例2There
are a lot of students ____ in the class room.
A talk B
talking C talked D to talk
解析：该题正确答案为B。There be句型为倒装句，可换为A lot of students are
talking in the class room. 又如：There is a lot of noise
heard out in the street.
