雅思阅读中常见句型
---主语从句及非限定性定语从句
主语从句(Subject Clause)
定义:如果一个句子在复合句中充当一个主语,那么这个句子就是主语从句.
第一部分：常规主语从句，即句子在复合句中充当一个主语
（1）That he finished writing the composition in such a short time surprised us all.
（2）Whether we will go for an outing tomorrow remains unknown.
（3）Who will be our monitor has't been decided yet.
（4） Whom we must study for is a question of great importance.
（5）What caused the accident remains unknown.
（6）Whatever you did is right.
（7）Whose watch was lost is unknown.
（8）What we need is time.
（9）What we need are good doctors.
小结:
（1)引导主语从句连词有that,whether,who,what,whatever等连词位于句首不能省略
（2)主语从句大多数情况下视为单三,但也有例外,如例9
第二部分：为了防止句子头重脚轻，通常把形式主语it放在主语位置，真正主语搁置于句末
（1）It is certain that he will win the match.
（2）It is true that he has made a very important discovery in chemistry.
（3）It is very likely that they will hold a meeting.
（4）It is strange that he should do that.
（5）It is important that we all should attend the meeting.
（6）It is strange that the man should have stuck to his silly ideas.
（7）It is a pity that we won't be able to go to the south to spend our summer vacation.
（8）It is still a mystery what caused the accident.
（9）It is said that he has gone to shanghai.(=He is said to have gone to shanghai)
（10）It is known to all that the gun powder was first invented by the Chinese.
（11）It is suggested that the work should be done with great care.
（12）It seems that he has seen the film.(=He seems to have seen the film)
（13）It happened that the two cheats were there. (=The two cheats happened to be there)
小结:
（1)以that 引出的主语从句,常以形式主语it引导. It is +形容词/名词/某些动词ed + that 从句.
（2) 在有些that从句中要用虚拟语气 (should+do/should+have done)例句4,5,6,11.
主语从句与宾语从句两者的用法和在句中的作用是不同的，下面从它们的各自用法，介绍：）~
一．主语从句
主语从句
定义:在句子中担当主语的是一个从句,这个从句就叫做主语从句。
主语从句是在复合句中充当主语的从句，通常放在主句谓语动词之前或由形式主语it代替，而本身放在句子末尾。
1. It 作形式主语和it引导强调句的比较
It 作形式主语代替主语从句，主要是为了平衡句子结构，主语从句的连接词没有变化。而it引导的强调句则是对句子某一部分进行强调，无论强调的是什么成分，都可用连词that。被强调部分指人是也可用who/whom。例如：
It is a pity that you didn’t go to see the film.
2. 用it 作形式主语的结构
(1) It is ＋名词＋从句
It is a fact that … 事实是…
It is an honor that …非常荣幸
It is common knowledge that …是常识
(2) it is ＋形容词＋从句
It is natural that… 很自然…
It is strange that… 奇怪的是…
(3) it is ＋不及物动词＋从句
It seems that… 似乎…
It happened that… 碰巧…
(4) it ＋过去分词＋从句
It is reported that… 据报道…
It has been proved that… 已证实…
3. 主语从句不可位于句首的五种情况
(1) if 引导的主语从句不可居于复合句句首。
(2) It is said , (reported) …结构中的主语从句不可提前。例如：
It is said that President Jingo will visit our school next week.
(3) It happens…, It occurs… 结构中的主语从句不可提前。例如：
It occurred to him that he failed in the examination.
(4) It doesn’t matter how/whether …结构中的主语从句不可提前。例如：
It doesn’t matter whether he is wrong or not.
(5) 含主语从句的复合句是疑问句时，主语从句不可提前。例如：
Is it likely that it will rain in the evening?
4. What 与that 在引导主语从句时的区别
What 引导主语从句时在句时在从句中充当句子成分，如主语．宾语．表语，而that 则不然。例如：
What you said yesterday is right.
二：宾语从句的几个特征：
1、引导词：
what\which\whose\when\whether\if\where
2、语序：宾语从句必须是用陈述语句。
如：
I think that you must work harder.
宾语从句的引导词、连接词的区别、否定转移等现象。
(1)表达时间的几个句型：一般用when或者是what time：
What time will the train leave?
由于时刻都是固定的，也可以用一般现在时代替一般将来时：
What time does the train leave?
(2)时间的表达方式：
8：19(nineteen past eight),7:57(three to eight)，在时间的中间也可以加上分的单词(minutes)
(3)had better +动词原型。意思是提要求，建议。但是上下级不能用这种方式，因为语气太重：
You had better give up smoking .
(4)sb leave sth +地点
I left my book in my classroom yesterday.
(5)may I have your name(address\age)?一般询问对方的年龄、名字等，不要习惯以前的问法，这样很不礼貌，而是要采访上面的问法。以前的习惯是：how old are you? \what's your name?
(6)修饰名词的代词次序：限-描-大-形---年---颜----籍----物--------类+名词：
this is a bridge.
This is a beautiful bridge
定语从句：
1)定语从句有限制性和非限制性两种。限制性定语从句是先行词不可缺少的部分，去掉它主句意思往往不明确；非限制性定语从句是先行词的附加说明，去掉了也不会影响主句的意思，它与主句之间通常用逗号分开，例如：
This is the house which we bought last month. 这是我们上个月买的那幢房子。（限制性）
The house, which we bought last month, is very nice.这幢房子很漂亮，是我们上个月买的。（非限制性）
2)当先行词是专有名词或物主代词（物主代词分物主代词分形容词性物主代词my, your, his, her, its, our, your, their和名词性物主代词mine, yours, his, hers, its, ours, yours, theirs）和指示代词（指示代词有this,that,these,those,such,same等）所修饰时，其后的定语从句通常是非限制性的，例如：
Charles Smith, who was my former teacher, retired last year. 查理·史密斯去年退休了，他曾经是我的老师。
My house, which I bought last year, has got a lovely garden. 我去年买的的那幢房子带着个漂亮的花园。
This novel, which I have read three times, is very touching. 这本小说很动人，我已经读了三遍。
3) 非限制性定语从句还能将整个主句作为先行词, 对其进行修饰, 这时从句谓语动词要用第三人称单数，例如：
He seems not to have grasped what I meant, which greatly upsets me. 他似乎没抓住我的意思，这使我心烦。
Liquid water changes to vapor, which is called evaporation. 液态水变为蒸汽，这就叫做蒸发。
说明：关系代词that和关系副词why不能引导非限制性定语从句。
2)as引导非限制性定语从句时与which的区别
①当主句和从句语义一致时，用as；反之，用which来引导非限制性定语从句。e.g.
He made along speech,as we expected.
He made along speech,which was unexpected.
②当非限制定语从句为否定时，常用which引导。
e.g.
Tom drinks a lot everyday,which his wife doesn’t like at all.汤姆每天喝很多酒，他妻子一点也不喜欢。
2.关系代词在从句中作主语时，从句的谓语动词单数还是用复数应由先行词决定。e.g.
The man who lives downstairs speaks English fluently.住在楼下的那个人英语说得很流利。
The students who are in GradeThree are going to climb the hill tomorrow.
3.定语从句有时不直接紧靠先行词，中间由一个定语、状语或谓语隔开。e.g.
There is an expression in his eyes that I can’t understand.
4.引导定语从句的关系副词有时可以用“介词+which”来代替。e.g.
October 1,1949 was the day on which(=when)the People’s Republic of China was founded.
5.当定语从句中谓语动词是带介词或副词的固定短语动词时，短语动词的各个固定部分不要拆开。e.g.
The sick man whom she is looking after is her father.
6.介词在关系代词前，只能用which和whom，且不能省略；介词在句尾，关系代词可有which,that,whom,口语中也可用who，且可省略。
e.g.
The man(whom/who/that)you were talking about has come to school.
as 用的地方比较少，as is known to all, as you know, as we know等等。as 经常指代一件事情，就是说as从句修饰的是前面或后面主句的一整句话。
which 用的地方指代的更多一点，可以指代一件事情，也可以指代一个事物，就是说which从句修饰的可以是前面的一个词语或者整个主句的句子。
which与as引导的非限制定语从句的异同
1．which引导的非限制性定语从句，先行词既可是物，也可以是一个句子，或句子的一部分
它在从句中充当主语、宾语或表语，这时从句对主句叙述的事进行补充说明，表示说话人对话语的看法、依据、解释或评论。
My house, which I bought last year, has got a lovely garden.我的房子有一个漂亮的花园，它是我去年买的。（which指代my house）
The boy made a hole in the wall, through which he could see what was happening inside the house.那个聪明的男孩在墙上打了个洞，他透过洞能看见房子里正发生的事。（which指代hole）
At noon they got to a hill, at the top of which stood a temple.中午他们来到一座小山，山顶上有个庙。（which指代hill）
They invited me to visit their country, which was very kind of them.他们邀请我访问他们的国家，这件事使我很感谢。（which指代整个主句阐述的事实）
He came back safely, which delighted us.他平安地回来了，这使我们很高兴。（which指代主句中阐述的事实）
She married again, which was unexpected.她又嫁人了，这是没料到的事。（which指代主句阐述的事实）
2．as也能引导非限制性定语从句，含有“正如……”的意味，在从句中充当主语、宾语或表语，它的先行词只能是一个句子，而不能是一个名词或代词，一般情况下，可以用which替代。
He saw the girl ,as / which he hoped he would.他看见了那位姑娘，这正是他希望的事。
He was not sick, as / which some of the other passengers were.他没有病，倒是其他旅客病了。
He married her, as / which was natural.他娶了她，这是自然的事。
3．as引导的非限制性定语从句可以放到句首，which则不能
As we have seen, oceans cover more than seventy percent of the earth.正如我们所知的那样，海洋占据了地球的70％。
As we all can see, great changes have taken place in China.正如我们有目共睹的，中国发生了巨大变化。
as引导从句放在句首，常见的短语有：
as is well known众所周知
as is often the case情况常常如此
as was mentioned above如下面提到的
as might be expected正如可能预料的
4．as在从句中作主语时，其谓语或者是行为动词的被动态，或者是be及其他连系动词
He came late again, as was expected.他又迟到了，正如预料的那样。
He married again, as seemed natural.他又结婚了，这是自然的事。
5．as在从句中作宾语，从句的谓语动词常是see, know, hear, watch, tell, remember, say等
He is a writer, as you may have heard.他是一位作家，正如你听到过的那样。
Light travels faster than sound, as we all know.正如我们所知的那样，光比声音传播得快。
6．当从句是“主语＋谓语＋宾语”结构时，as一般不用于充当从句的主语
He changed his mind, which（不用as）made me very angry.他改变了主意，这使我很恼火。
It was raining hard, which（不用as）kept us indoors.天正下着大雨，这使我们不能外出。
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