/ɪt; ɪt/
pers pron 人称代词 (used as the subject or object of a v or after a prep 用作动词的主体或宾语或用于介词之後)
1 (a) animal or thing mentioned earlier or being observed now 它
*`Where's your car?' `It's in the garage.' ｀你的汽车在哪儿呢?＇｀在车库里＇.
* Did you hit it? 你打中了吗?
* Fill a glass with water and dissolve this tablet in it. 倒杯水把药片放进去溶解了.
* We've got 500. Will it be enough for a deposit? 我们有500英镑了. 够不够作押金的?
(b) baby, esp one whose sex is not known or unimportant 他（指婴儿, 尤指性别不详或无所谓时）
*Her baby's due next month. She hopes it will be a boy. 她怀的孩子该下月出生. 她希望是个男孩儿.
* The baby next door kept me awake. It cried all night. 隔壁的孩子吵得我睡不着觉. 他整夜哭个没完.
2 fact or situation already known or implied （已知的或暗含的）事实或情况
*When the factory closes, it (ie this event) will mean
500 redundancies. 工厂一旦关闭, 那就意味着要有500人遭遣散.
* Yes, I was at home on Sunday. What about/of it? 是啊, 我星期天在家来着. 怎么了?
3 (used to identify a person 用以确定一人的身分)
*It's the milkman. 那是送牛奶的.
* It's Peter on the phone. 是彼得打来的电话.
* Was it you who put these books on my desk? 是你把这些书放到我桌上的吗?
4 (idm 习语) this/that is `it
(a) this/that is what is required 这[那]正是所需要的
*We've been looking for a house for months and I think this is it. 我们找房子已经找了好几个月了, 我看这所就是我们要找的.
(b) this/that is the reason for the lack of success 这[那]正是未能成功的原因
*That's just it I can't work when you're making so much noise. 原因就在这里--你弄出这么大的声音, 我工作不了.
(c) this/that is the end 这[那]就是终结
*I'm afraid that's it we've lost the match. 我看到此为止了--这场比赛我们已经输了.

/ɪt; ɪt/
pron
1 (used in the normal subject or object position to indicate that a longer subject or object has been placed at the end of a sentence 作长的主语或宾语的先行代词)
*It appears that the two leaders are holding secret talks. 两位领导人好像在举行秘密会谈.
* Does it matter what colour it is? 是什么颜色有关系吗?
* It's impossible (for us) to get there in time. （我们）不可能及时赶到那里.
* It's no use shouting. 叫喊并没有用.
* She finds it boring staying/to stay at home. 她觉得待在家中很无聊.
* I find it strange that she doesn't want to travel. 她竟不想旅游, 我觉得很奇怪.
2 (used in the normal subject position to make a statement about time, distance or weather 指时间、距离或天气时作句中主语)
*It's ten past twelve. 现在十二点十分.
* It's our anniversary. 今天是我们的周年纪念.
* It's two miles to the beach. 离海滨有两英里远.
* It's a long time since they left. 他们走後很久了.
* It was raining this morning. 今晨下雨来着.
* It's quite warm at the moment. 现在天气很暖和.
* It's stormy out at sea. 海上有风暴.
3 circumstances or conditions; things in general 环境或情况; 泛指的事物
*If it's convenient I can see you tomorrow. 要是方便的话, 我明天可以见你.
* It's getting very competitive in the car industry. 汽车工业方面的竞争日益加剧.
4 (used to emphasize any part of a sentence 用以强调句中任何部分)
*It's `Jim who's the clever one. 聪明的是吉姆.
* It's `Spain that they're going to on holiday. 他们假日要去的地方是西班牙.
* It was three weeks `later that he heard the news. 三个星期以後他才听到这消息.

pron [used as subject or object]
[Language: Old English;Origin: hit]
used to refer to a thing, animal, situation, idea etc that has already been mentioned or is already known about
　'Where's your office?' 'It's on the third floor.'
　I love the spring - it's a wonderful time of the year.
　There were people crying, buildings on fire. It was terrible!
　Don't blame me. It wasn't my idea.
　This little beast is a lemur and it lives in Madagascar.
used to refer to the situation that someone is in now, or what is happening now
　I can't stand it any longer. I'm resigning.
　How's it going, Bob? I haven't seen you for ages.
　And the worst of it is the car isn't even paid for yet.
　Stop it, you two. You're just being silly.
used as the subject or object of a verb when the real subject or object is later in the sentence
　It worries me the way he keeps changing his mind.
　What's it like being a sailor?
　Apparently it's cheaper to fly than to go by train.
　It's a pity you couldn't come.
　It seems that we are not welcome here.
　I found it hard to concentrate.
used as the subject of a sentence when you are talking about the weather, the time, a distance etc
　Is it still raining?
　It was 4 o'clock and the mail still hadn't come.
　It's my birthday today.
　It's over 200 miles from London to Manchester.
　It gets dark very early in the winter.
　It's three years since I last saw her.
used with the verb 'be' to emphasize that you are talking about one particular thing, person, group etc and not any other
　It's Lawrence you should be talking to.
　It was malaria that killed him.
　It was in New Zealand that Elizabeth first met Mr Cronje.
used to refer to a baby when you do not know what sex the baby is
　What will you call it if it's a boy?
a) used to say who a person is
　'Who's that over there?' 'It's Robert Morley.'
b)spoken used to say who is speaking, especially on the telephone
　Hello, it's Frank here.
　It's all right, it's only me.
informal used to refer to sex
　Have you done it with him yet?
if it wasn't/weren't for sb/sthalsoif it hadn't been for sb/sth
used to say who or what prevents or prevented something from happening
　We would have arrived much earlier if it hadn't been for the snow.
informal a particular ability or quality that is needed in order to do something
　In a job like advertising, you've either got it or you haven't!
this is it
spoken used to say that something you expected to happen is actually going to happen
　This is it, boys, the moment we've been waiting for.
that's it
spokena) used to say that something is completely finished or that a situation cannot be changed
　That's it then. There's nothing more we can do.
b) used to tell someone that they are doing something correctly
　Slowly...slowly. Yeah, that's it.
c)alsothat does it
used when you are angry about a situation and you do not want it to continue
　That's it. I'm leaving.
think you're itinformal
to think you are more important than you are
　Just because he got a higher mark he really thinks he's it.