conjunction连词
用句子替代单词，形容词<-->定语从句，副词<-->状语从句，名词<-->名词性从句；
一、名词性从句
1、主语从句
引导主语从句连词有that|whether|who|what|whatever等；
主语从句大多数情况下视为第三人称单数，但在连接代词what引导的主语从句后谓语动词的单复数形式要根据句意而定；
为了防止句子头重脚轻，通常把形式主语it放在主语位置（句首位置），真正主语后置（搁置于句末）；
It is certain that (he will win the match).他一定会赢得这场比赛的
It is truethat(he has made a very important discoery in chemistry).他的确在化学领域有了一个伟大的发现
It is very likely that they will hold a meeting.他们很有可能会举行一场会议
It is strange that he should do that.他竟然那样做是很奇怪的
It is important that we all should attend the meeting.重要的是我们都应该参加会议
It is strange that the man should have stuck to his silly ideas.真奇怪，这个人竟然坚持自己愚蠢的想法
It is said that he has gone to shanghai.据说他已经去上海了
It is known to all that the gun powder was first invented by the Chinese.所有人都知道火药最初是由中国人发明的
It is suggested that the work should be done with great care.建议工作应该被小心地完成
主语从句的时态不受主句时态的影响和限制；
(That hefinished writing the composition in such a short time)surprisedus all.他在如此短的时间内写完作文使我们十分惊讶
(Whether wewill go for an outing tomorrow) remainsunknown.我们明天是否会去郊游仍旧未知
(What caused the accident) remains unknown.事故的起因是未知的
(Whatever you did) is right.你做的任何事都是正确的
Whom the watch belongs to is unknown.手表的归属是未知的
it作形式主语和强调句的区别：
1 主语从句常用it作形式主语，一般常用句型it is + 名词|形容词|过去分词 + 主语从句；
It is still a question whether she will come or not.
It is strange that you should like him.
It is still unknown which team will win the match.
比较常见的结构：
It turned out that...
It has been proved that...
It happened|occurred that...
It is well-known that...等
2 强调句的结构是it + be + 被强调部分 + that + 从句；
It is the times that produce their heroes.强调主语，时势造英雄
It is English that Prof.Lin teaches us.强调宾语
It was in shanghai that I saw the film强调状语
3 判断是否是强调句的方法：将it、be、that去掉看句子是否完整，仍完整是强调句，否则是主语从句；
用it作形式主语的常见结构：
1) it is + 名词 + that从句，如：
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 + that从句，如：
It is natural that...，很自然...
It is strange that...，奇怪的是...
3) it + 不及物动词 + that从句，如：
It seems that...，似乎...
It happened that...，碰巧...
4) it is + 过去分词 + that从句，如：
It is reported that...，据报道...
It has been proved that...，已证实...
主语从句不可位于句首的五种情况：
1) if引导的主语从句；
2) it is said|reported...，It is said that President Jingo will visit our school next week.
3) It happens...，It occurs...，It occurred to him that he failed in the examination.
4) It doesn't matter how|wheter...，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，Is it likely that it will rain in the evening?
what与that在引导主语从句时区别：
what引导主语从句时在从句中充当句子成分，如主语、宾语、表语；
而that在从句中不充当成分；
What you said yesterday is right.
2、表语从句
是用一个句子作为表语；
关键记住：从句连词比谓语动词少一个；
The problemis howwe can get the things we need.从句连词how谓语动词is和can
The scissors are not whatI need.从句连词what谓语动词are和need
What I told him was thatI would find him a good play.从句连词that和what谓语动词told和was和would find
That is whatI want to tell you.从句连词what谓语动词is和want
That is whyshel failed to pass the exam.从句连词why谓语动词is和failed
表语的种类：
1) 名词作表语
Africa is a big continent.非洲是个大洲
2) 代词作表语
What's your fax number?
Who's your best friend?
3) 形容词作表语
I feel much better today.我今天感觉好多了
He id old but he is healthy.他很老但他很健康
4) 数词作表语
She was the firstto learn about it.她是第一个知道的人
5) 非谓语动词作表语
Her job is selling computers.
Our next step was to get raw materials ready.我们下一步是把原料准备好
6) 介词短语作表语
The patient is out of danger.病人脱险了
I don't feel at ease.我感到不自在
7) 副词作表语
The sun is up.太阳升起来了
I must be off now.我得走了
引导名词性从句时if|wheter（是否）用法辨析：
if不能引导表语从句，用whether来引导；
引导宾语从句时if|whether可互换，但介词后面的宾语从句只能用whether来引导；
位于句首的主语从句只能用whether来引导，同位语从句也只能用whether来引导；
The question is if the enemy is marching towards us. # 错误
The question is wheteherthe enemy is marching towards us. # 正确
This is what I want.这就是我想要的
Next Sunday is whenwe shall meet.下周日是我们见面的时间
My problem is which computer to choose.我的问题是不知道选哪个电脑好
The argument is whether it rains tomorrow.明天是否下雨是争论的内容
What the police want to know is when you entered red the room.警察想知道的是你什么时候进的房间
3、宾语从句
语序：主语 + 谓语+ 宾语从句；
时态：1当主句是一般现在时或一般将来时的时候，从句可以是任何时态；2当主句是一般过去时的时候，从句时态必须是过去时范围的时态（一般过去时|过去进行时|过去完成时|过去将来时）；
连接词：根据中文意思决定；
宾语从句的种类：
动词的宾语从句，介词的宾语从句，形容词的宾语从句（be + adj. = 动作，I am aware.，I am glad.，I am eager to do sth.）；
He told me that he would go to the college the next year.双宾
I have found out that all the tickets for the concert have been sold out.
I am afraid that he can't pass the coming exams without good preparation.
it作形式宾语：
动词find|feel|consider|make|believe等后面有宾语补足语时，则需要用it作形式宾语而将that宾语从句后置；
I think it necessary that we take plenty of hot water every day.
I feel it a pity that I haven't been to the get-together.
We all find it imporant that we (should) make a quck decision about this matter.
否定转移：
think|believe|imagine|suppose|consider|expect|guess等；
I don't think he will come to my party.
I dont' believe that man is killed by Jim, is he?
that不可省略：
1) 当主句谓语动词带有2个或2个以上宾语从句时，可以省略第1个that，其他不能省略；
I believe (that) you have done your best and thatthings will get better.
2) 当it作形式宾语时；
She made it clear that she had nothing to do with him.
3) 当宾语从句前置时（口语时高频）；
That our team will win, I believe.
4、同位语从句
定义：
1在复合句中用作同位语的从句；
2一般跟在某些名词后面，用以说明该名词表示的具体内容；
名词后的从句，如果是解释（是）是同位语，如果是修饰（的）是定语；
the fact that I pass the exam.同位语
the fact that I pass the exam is true.定语
I heard the news that our team had won.我听到了我们队获胜的消息
I had no idea that you were here.我不知道你在这里
构成：
可以跟同位语从句的名词通常有：news|idea|fact|promise|question|doubt|thought|hope|message|suggesiton|words消息|possibility等；
I've com from Mr. Wang with a message that he won't be able to see you this afternoon.
同位语的种类：
1) 名词作同位语；
Mr wang, my child's teacher, will be visiting us on Tuesday.王先生，我孩子的老师，星期二要来看我们
2) 名词性短语作同位语；
I, the oldest girl in the family, always had to care for the other children.我，作为家里最大的女孩，问题要照料家中的其他孩子
3) 直接引语作同位语；
But now the question comes to their minds, "Did she die young because she was a clone?"但是现在他们不得不思考这样的问题“多莉早死是因为它是一只克隆羊吗？”
4) 句子作同位语；
The girls were surprised at the fact that ocean ships can sail up the Great lakes.巨大的海轮可以开到五大湖，让表姐妹俩感到吃惊
