名词性从句：
主语从句、宾语从句、表语从句和同位语从句在句中的作用相当于一个名词，所以把它们统称为名词性从句
一、宾语从句
注意一：引导词的选择：
1). You’ll have to decide_____ car we’ll use, yours or mine.
2). You’ll have to decide_____ car we’ll use, the old one or the new one.
3). You’ll have to decide_____ we’ll use the new car for.
4). You’ll have to decide_____ we’ll use the new car.
A. which B. what C. whose D. whether
提醒1：check/make sure 不用if/whether 引导从句，而用that:
Check that everything is in order, please.
Make sure that the door is locked before you leave the lab.
提醒2：doubt：肯定：______ 否定/疑问：______
I doubt ______ she is liked. I don’t doubt ______she is liked.
Do you doubt ______she is liked?
提醒3： I am sure _____; I am not sure ______
I am not sure whether/if the news is true. I am sure that the news is true.
He said he would come if he had time.
例外：1. 当从句为客观真理或普遍事实时， 用一般现在时：
The teacher said that the earth turn around the sun.
2. 当主句谓语动词为一坚持、二命令、三建议、四要求等动词时， 从句常用should+v原
He demanded that they should be there on time.
注意三：从句的语序：所有从句都用陈述句语序：
I don’t know where he has gone.
注意四：混合型的宾语从句：
1. 否定的转移：当主句的谓语动词为think, suppose, expect, believe, imagine等时，其后的宾语从句为否定句时，常将否定词not 从从句中转移到主句中，构成否定转移：
We don’t think there is anything of interest in your picture.
2. 插入语：wh- +do you think/believe/suppose/suggest…?
What do you suppose they need?
Where do you think the boy has gone?
注意五：in that : 在于，因为：引导宾语从句
Human beings are different from animals in that they can use languages as a tool to communicate.
注意六：形式宾语的运用：
1. S+V+it+adj/n+to do/doing/从句
He made it clear that he would leave office soon.
Don’t take it for granted that your parents should do everything for you.
2. 固定：like, dislike, hate, appreciate, depend on, rely on, see to 等+it+ 从句
I would appreciate it if you could call me in advance.
I hate it when people talk with their mouths full.
注意七：
在think, imagine, suppose, guess, hope 等词后，以及在I’m afraid等后， 可以用so 代替上文宾语从句所表达的肯定的意思，用not 表达否定的意思：
I think so. /I don’t think so=I think not.
I hope so. /I hope not.(fear/ guess/ I am afraid)
注意八：宾语从句的主语是that 时，that 不可省略：
People say that that was how the Chinese first raised silkworms.
注意九：介词后一般不跟that 引导的宾语从句但可跟wh-开头的词引导的宾语从句：
Whether you will succeed depends on whether you will take pains.
Please remind me of what he once said to me.
但是but, except, besides, in 后可以跟that 引导的宾语从句，that 不省
We know nothing about him except that he is from Beijing.
Human beings are different from animals in that they can use languages as a tool to communicate.
注意十:that 引导的宾语从句在口语或非正式文体中that 可省略，但一个动词后有两个或以上的由suggest的名词that 引导的宾语从句时，第一个that 可以省略，第二个起不省。
The report shows (that) we are making some progress but that we need to make greater efforts.
如果that 从句被短语等与主句分开，或者从句中含有另一个从句，that 不可省略。
They promised once again that this would not happen again.
I dare say that if you don’t work hard you will fail.
二、表语从句
一个句子作表语就叫表语从句。表语从句是解释说明主语的具体内容。
What we don’t doubt is that the patient will soon recover.
Chances are that two out of ten youth are addicted to smoking.
注意一：that, why 和because 的选择：
1.表示原因的reason, cause 名词或从句作句子的主语时，其后的表语从句常用that 引导，不可误用because.
1. The reason why he hasn’t come is because he has not received the invitation. (that)
2. I was late for school this morning. That’s why/because I stayed up too late last night.
3. I stayed up too last night. That’s why/because I was very late for school this morning.
(because引导表语从句时常用于That’s bcause…结构中，说明产生上述结果的原因；why引导的名词性从句说明由上述原因导致的某种结果。
注意二：
1.当主语时suggestion, plan, order, idea 等词时， 表语从句的谓语要有虚拟语气，即should+动词原形，should可省略。
My suggestion was that we (should) go to see the film together.
2. as if 也可以引导表语从句：
It looks as if it is going to snow.
It looked as if he hadn’t eaten for a week.
三、主语从句：
四个误区：
误区一、误作特殊疑问句：
When will they come back is puzzle./ When they will come back is a puzzle.
误区二、机械套用：
It was uncertain that when they did it./ It was uncertain when they did it.
误区三、谓语动词形式误用复数：
Why he made so many mistakes are not clear./ Why he made so many mistakes is not clear.
误区四、与as…从句混杂
As/ It is known to us that the earth is round./ As/ It is known to us, the earth is round.
注意一：that 引导的主语从句往往很长，放在句首显得头重脚轻。因此，常用it 作形式主语，代替that 引导的主语从句，将that 从句后置。
1. It is +adj +that从句：1）adj: likely, possible, probable, certain, obvious 等+从句，时态一致
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