【初中生必会英语知识】十分钟掌握-it句型
it句型
一、it 作形式主语
当动词不定式、动名词或从句作主语时,通常把它们放在谓语之后,而用it作句子的形式主语。
1. It's +adj. + to do sth.
It's easy to pick up BBC English programmes.收听 BBC 英语节目是很容易的。
2. It's + adj. + of sb. to do sth.
此句型中形容词有:kind,nice,good,wrong,clever, careful, po lite,foolish 等。
It's foolish of you to do like this.你这样做真是太傻了。
3. It's + adj. + for sb. to do sth.
此句型中形容词有:difficult,hard,easy,important,impossible, dangerous 等。
It's dangerous for you to play the football in the street.在街道上踢足球是危险的。
4. It's + adj. /n. + doing sth.
此句型中常用的形容词或名词有:useless，no use,no good,dan gerous,a waste of 等。
It's no use arguing with him because he will never change his mind .同他争吵没有用,因为他从来不改变自己的主意。
It's dangerous playing with fire.玩火是危险的。
5. It is worthwhile + 动名词(不定式)
It is worthwhile seeing the film.看这部电影值得。
6.It is + 形容词/过去分词 + that 从句
常用的形容词有:strange,surprise,evident,obvious,good, won- derful 等。
It isstrange that Li Ming didn't come to school yesterday真奇怪,昨天李明没来上学。
It is evident that Jack has returned.显然,杰克已经回来了。
7. It doesn't matter to sb. whether..
It doesn't matter to me whether you will come or not.你来不来对我没关系。
8. It is up to sb. to do sth.
It is up to me to help the students study English.帮助学生学英语是我的责任。
9. It's time to do sth. 该……
It's time to make a decision. 该做出决定了。
10. It's time for sb. to do sth. 该……的时间到了
It's time for us to have lunch. 我们该吃午饭了。
二、it 作形式宾语
当复合宾语中的宾语是不定式、动名词或宾语从句时,往往把宾语放在它的补足语后面,而用作形式宾语,放在宾语补足语之前。如:
The chairman thought it was necessary to invite Professor Smith to speak at the meeting.主席认为邀请史密斯教授在会议上发言是有必要的。
I found it very interesting to study English.我发现学英语很有趣。
三、it的其他用法
1.it 与强调句
这是近年来高考对特殊句式考查频率最高的一个语法结构,其结构是“It is/was +被强调部分 + that 从句”。
Itis this grammar book that helped me (to) improve my English.就是这本语法书帮我提高了我的英语水平。
It was not until I got home that I realized I had lost the keys.直到我到家了，我才意识到钥匙丢了。
2.it 与连词 since/before/when/until 构成的状语从句。
通常主句使用现在完成时或一般过去时,而从句使用一般过去时。如:
It is three years since we began to study English.自从我们开始学英语,已经三年了。
Isaw Wang Lin yesterday. It was five years since I saw him last time .昨天我见到王林了。自从我上次见到他,已经五年了。
特别警示:
在 since 从句中,短暂性动词用于一般过去时或延续性动词用于现在完成时,表示“某人做某事已有多久了”;延续性动词用于一般过去时,则表示“某人不做某事已有多久了”。如:
It is three years since he left Shanghai.=It is three years since he has been away from Shanghai.= It is three years since he lived in Shanghai.他离开上海已经三年了。
It is ten years since he came to Beijing.= It is ten years since he has been in Beijing他来北京十年了。
It is two months since he fell ill.= It is two months since he has been ill. 他病两个月了。
It is two months since he was ill. 他的病已经好两个月了。(简记为:延续性动词用于一般过去时,表达的意义相反。)
It was long time before they met again.很长时间后他们才见面。
It was 1945 when the Second War of the World ended.1945年第二次世界大战结束。
→The teacher said to her mother that she had gone home.
二、时态变化规律:直接引语变为间接引语时,时态要在
原来时态的基础上往前推移一个时态(简记为:时态向前推一步)。
直接引语时态 间接引语时态
一般现在时 一般过去时
一般将来时 过去将来时
现在进行时 过去进行时
现在完成时 过去完成时
过去完成时 过去完成时
助记歌诀:
“直引”“过去”时具体，主句“过去”从“过去”。如果“直引”述“真理”，总是“现在”作谓语。“间引”时态依啥变?“主句谓语”时态看:“一般现在”“将来时”,“间引”时态不用变。主句谓语“过去”用，相应“过去”来呼应。查查时态对应表，记住规律很轻松。
说明:
1.当主句是一般过去时,间接引语的时态要变为相应的过去时。如:
She said,“They are quarreling among themselves.”
She said they were quarreling among themselves.
Tom said,“The manager has gone to Shanghai.”→Tom said the manager had gone to Shanghai.
2.当直接引语是客观事实、科学真理以及格言时,时态不变。如:
He said,“Light travels faster than sound.”→He said light travels faster than sound.
The teacher said,“Where there is a will, there is a way.”→The teacher said where there is a will there is a way.
3.It’s +名词(a pity,a shame, a fact, an honor, a wonder, a good thing, good news...) + that 从句,构成同位语从句。
It's a fact that English is being accepted as an international language.英语是国际语言这一事实已被认可。
4.It's time + that 从句,构成虚拟语气,that 从句谓语用一般过去时或“should + 动词原形”。
It's time that you studied hard. 你早该努力学习了。
It's high time that we should get up.我们早就该起床了。
5.It is/was the first (second,third.….)time + that 从句,that 从句用现在或过去完成时。
It is the first time that I have met the foreigners.这是我第一次遇到外国人。
It was the second time that I had been to Hangzhou.这是我第二次去杭州。
6. It appears/seems that...“似乎……,好像” It happens that…“碰巧……,恰好……”
It turns out that...“结果是……,证明是……”此句型中的 that-clause,通常被看成是表语从句。
Wang Lin came to see me last Sunday.
It happened that I wasn't at home.上星期天王林来看我,碰巧我不在家。
It seems that it is going to rain tomorrow.明天好像要下雨。
7. It goes without saying that...=It is needless to say that………是不用说的
It goes without saying that each student should master a foreign language.不用说每个中学生必须学一门外语。