It的基本用法

注意：It
is… for sb. to do sth.
It is …of sb. to do sth.
It + be + adj. for sb to do sth 某人做某事……
It + be + adj. of sb to do sth 某人做某事……
It is hard for him to make up his mind. 他很难下定决心。 It was foolish of her to say such a thing. 她说那样的话，真是太蠢了。 【说明】介词 of 与 for 的区别是：of 用于指 某人的性格、属性、特征等，介词for表示对象，意 为“对……来说”
我有一本词典，但把它借给玛丽了。
I haven’t a dictionary; can you lend me one? 我没有词典，你能借我一本吗?
II. It用于强调句型；
It is/was+被强调部分（通常是主语、宾语，状语） +that/who+句子的其余成分。
如： I met a strange man in the street 主语 宾语 地点状语
常见的有: take it for granted, bring it to sb’s attention, owe it to sb 等。
IV. It用于
某些固定句式；
指时间时用于下列句型 ⑴ It + be + some time + since 短语或从句 It is a long time since the last meeting. It is (has been) fifteen years since he left. 注意：若从句中谓语动词是非延续性动词，意为 “做某事已有多长时间”。 若从句中谓语动词是延续性动词，意为 “不做某事已有多长时间”。 It’s two years since he joined the army. 参 军 It’s two years since heห้องสมุดไป่ตู้was in the army. 伍 退 It’s two years since she got married. 结 婚 It’s two years since she was married. 离 婚
-- It is me.
注意：表示未知或面目不详，身份不明的人。 Who is it speaking? (打电话用语)
４指时间、距离、地点、天气、温度、环境等 --What’s the time now? --It’s ten past eight. （时间） It was very quiet in the café. （环境） It’s about ten minutes’ walk from here. （距离）
4. 动词 + it + 介词短语+ that
I took it for granted that he would help us. 我认为他会帮助我们的。 If you dare cheat again, I will bring it to your mother's attention. 如果你敢再作弊,我会将此 事告知你妈妈。
误用形式主语的几种情形
(1) 在该用it作形式主语的地方而误用其他词：
Is __ necessary to tell his father everything?
A. it
B. that
C. what
D. he
此题的正确答案应是A (it用作形式主语)， 而不能选D。 (2) 在不该用形式主语的地方而误用形式主语： _ must be something wrong with the machine. A.There B. It C. He D. That
A. it B. that C. these D. them
常见的有enjoy, hate, love, like, dislikeappreciate, prefer 等。
2. I’d appreciate _ if you would turn the radio down.
A. that C. this B. it D. you
yesterday.
时间状语 注意：强调句强调除谓语以外的所有成分。
Is / Was it +被强调部分+that /who…? When .Where How Why+is was it that…?
Who was it that you met in the street yesterday?
It was already nine o’clock when we got home.
(4)It is (was) time for sth. It is (was) time to do sth. It is (was) time for sb. to do sth. It is (was) time that 从句(虚拟语气) It’s time for lunch. 该吃午饭了。 It’s time for us to have a rest.是休息的时候了。 It’s time that we went home. 该回家了。 （should go）
III. It 形 式 作 用 ： 形式主语, 形式宾语;
1.作形式主语，代表动词不定式、
动名词或主语从句
It is important to study English. It is no use crying over spilt milk. It is a pity that you’ve missed such a wonderful film. (主语从句)
两者均可代替前面提到的事物，区别是：
it指的是与前面已提到的事物为同一物，
此时的it等于“the (this, that, my...)+名词”；
而one 指的是与前面已提到的事物为同一类物，
此时的one等于“a+名词”。比较：
I have a dictionary but I’ve lent it to Mary.
相关链接 1.Was it in this place ___ the last emperor died? A. that B. what C. in which D. where 2.___ was simply for the reason ___ I wouldn’t tell him the truth. A. This, which B. That, so C. It, that D. This, why 3.--________ makes her different from the other students? --Honesty, I think. A. How is it that B. How is that C. What is it that D. What is that
前一句填C，as用以引导一个非限制性定语从句；后一句填A，it 为形式主语，真正的主语是其后的that从句。
______ is difficult to persuade her to stay.
______ is difficult is to persuade her to stay.
A. It B. What C. He D. That
2. 动词 + it + when (if)-从。
We really appreciate it when she offered to
help. 她来帮忙了，我们十分感激。
I’d prefer it if I didn’t have to do so much work. 要 是我不必做那么多工作，好就太好了。 ［链接高考］ 1. I hate ______ when people talk with their mouths full.(1998年NMET)
it用作形式宾语的四个特殊句式
1. 动词+ it + thatI take it (that) he will come on time. 我认为他会准时来的。 You can put it that it was arranged before. 你可以说这是以前安排的。
常见的有:
have, take, put, help 等。
５、指代整个句子的内容
a. Her mother kept telling her not to go out at night,
but it didn’t help. b. --We’ve been invited to the ball at the palace.
--Really? I can’t believe it.
［链接高考］
Helen is much more kind to her youngest child than to the others, _______ of course, makes the others
unhappy.
A. who
B. she
C. which
D. that
指物时与one的区别
It 用法完全归纳
考点目标
I. It 指代作用 II. It用于强调句型； III. It形式作用：形式主语,形式宾语; IV.It用于某些固定句式；
I、It 指代作用
1.用于指代事物
This is not my book. It is Mary’s.
2.用于指代动物，婴儿 --Whose jacket is that? It is hers. ３.用于指人 --Who’s knocking at the door?
前一句填A，it为形式主语；后一句填B，what用以引导主语从句。 注意后一句比前一句在不定式前多了个is