高中英語名詞性從句的辨別
主語從句
主語從句是在復(fù)合句中充當(dāng)主語的從句球榆，通常放在主句謂語動詞之前或由形式主語it代替随抠，而本身放在句子末尾。
1. It 作形式主語和it引導(dǎo)強調(diào)句的比較荸型。
It 作形式主語代替主語從句盹靴，主要是為了平衡句子結(jié)構(gòu)，主語從句的連接詞沒有變化瑞妇。而it引導(dǎo)的強調(diào)句則是對句子某一部分進行強調(diào)稿静，無論強調(diào)的是什么成分，都可用連詞that辕狰。被強調(diào)部分指人是也可用who/whom改备。
例如：
It is a pity that you didn’t go to see the film.
It doesn’t interest me whether you succeed or not.
It is in the morning that the murder took place.
It is John that broke the window.
2. 用it 作形式主語的結(jié)構(gòu)。
(1) It is +名詞+從句
It is a fact that … 事實是…
It is an honor that …非常榮幸
It is common knowledge that …是常識
(2) it is +形容詞+從句
It is natural that… 很自然…
It is strange that… 奇怪的是…
(3) it is +不及物動詞+從句
It seems that… 似乎…
It happened that… 碰巧…
(4) it +過去分詞+從句
It is reported that… 據(jù)報道…
It has been proved that… 已證實…
3. 主語從句不可位于句首的五種情況柳琢。
(1) if 引導(dǎo)的主語從句不可居于復(fù)合句句首绍妨。
(2) It is said ， (reported) …結(jié)構(gòu)中的主語從句不可提前柬脸。
例如：
It is said that President Jingo will visit our school next week. (right)
That President Jiang will visit our school next week is said. (wrong)
(3) It happens…他去， It occurs… 結(jié)構(gòu)中的主語從句不可提前。
例如：
It occurred to him that he failed in the examination. (right)
That he failed in the examination occurred to him. (wrong)
(4) It doesn’t matter how/whether …結(jié)構(gòu)中的主語從句不可提前倒堕。
例如：
It doesn’t matter whether he is wrong or not. (right)
Whether he is wrong or not doesn’t matter. (wrong)
(5) 含主語從句的復(fù)合句是疑問句時灾测，主語從句不可提前。
例如：
Is it likely that it will rain in the evening? (right)
Is that will rain in the evening likely? (wrong)
4. What 與that 在引導(dǎo)主語從句時的區(qū)別。
What 引導(dǎo)主語從句時在句時在從句中充當(dāng)句子成分媳搪，如主語.賓語.表語铭段，而that 則不然。
例如：
1) What you said yesterday is right.
2) That she is still alive is a consolation.
賓語從句
賓語從句就是在復(fù)合句中作賓語的名詞性從句秦爆，通常放在主句謂語動詞(及物動詞)或介詞之后序愚。
1. 作動詞的賓語。
(1) 由that引導(dǎo)的賓語從句(that 通车认蓿可以省略)
例如：
I heard that be joined the army.
(2) 由what爸吮， whether (if) 引導(dǎo)的賓語從句
例如：
1) She did not know what had happened.
2) I wonder whether you can change this note for me.
(3) 動詞+間接賓語+賓語從句
例如：
She told me that she would accept my invitation.
2. 作介詞的賓語。
例如：
Our success depends upon how well we can cooperate with one another.
3. 作形容詞的賓語望门。
例如：
I am afraid (that) I’ve made a mistake.
That 引導(dǎo)的從句常跟在下列形容詞后作賓語：
Anxious形娇， aware， certain筹误， confident桐早， convinced， determined厨剪， glad哄酝， proud， surprised丽惶， worried炫七， sorry， thankful钾唬， ashamed， disappointed侠驯， annoyed抡秆， pleased， hurt吟策， satisfied儒士， content 等。也可以將此類詞后的that 從句的看作原因狀語從句檩坚。
4. It 可以作為形式賓語着撩。
It 不僅可以作為形式主語，還可以作為形式賓語而真正的賓語that 從句則放在句尾匾委，特別是在帶復(fù)合賓語的句子中拖叙。
例如：
We heard it that she would get married next month..
5. 后邊不能直接跟that 從句的動詞。
這類動詞有Allow赂乐， refuse薯鳍， let， like挨措， cause挖滤， force崩溪， admire， condemn斩松， celebrate伶唯， dislike， love惧盹， help乳幸， take， forgive等岭参。這類詞后可以用不定式或動名詞作賓語反惕，但不可以用that引導(dǎo)的賓語從句。
例如：
I admire their winning the match. (right)
I admire that they won the match. (wrong)
6. 不可用that從句作直接賓語的動詞演侯。
有些動詞不可用于“動詞+間接賓語+that從句“結(jié)構(gòu)中姿染，常見的有Envy， order秒际， accuse悬赏， refuse， impress娄徊， forgive闽颇， blame， denounce寄锐， advise兵多， congratulate等。
例如：
He impressed the manager as an honest man. (right)
He impressed the manager that he was an honest man. (wrong)
7. 否定的轉(zhuǎn)移
若主句謂語動詞為Think橄仆， consider剩膘， wuppose， believe盆顾， expect怠褐， fancy， guess您宪， imagine等奈懒，其后的賓語從句若含有否定意義，一般要把否定詞轉(zhuǎn)移到主句謂語上宪巨，從句謂語用肯定式磷杏。
例如：
I don’t think this dress fits you well.(我認(rèn)為這件衣服不適合你穿。)
表語從句
表語從句在復(fù)合句中作表語的名詞性從句揖铜，放在系動詞之后茴丰，一般結(jié)構(gòu)是“主語+連系動詞+表語從句”。可以接表語從句的連系動詞有be贿肩， look峦椰， remain， seem等汰规。引導(dǎo)表語從句的that程拦Γ可省略。另外溜哮，常用的還有the reason is that… 和It is because 等結(jié)構(gòu)滔金。
例如：
1) The question is whether we can make good preparation in such a short time.
2) This is why we can’t get the support of the people
3) But the fact remains that we are behind the other classes.
4) The reason he is late for school is that he missed the early bus.
同位語從句
同位語從句就是在復(fù)合句中作名詞的同位語的名詞性從句。
1. 同位語從句的功能茂嗓。
同位語從句對于名詞進一步解釋餐茵，說明名詞的具體內(nèi)容，一般由that引導(dǎo)述吸。
例如：
1) The king’s decision that the prisoner would be set free surprised all the people.
2) The order that all the soldiers should stay still is given by the general.
2. 同位語在句子中的位置忿族。
同位語從句有時可以不緊跟在它所說明的名詞后面，而是被別的詞隔開蝌矛。
例如：
He got the news from Mary that the sports meeting was put off.
3. 同位語從句與定語從句的區(qū)別道批。
(1) 定語從句中的that既代替先行詞，同時以在從句中作某個成分(主語或賓語)入撒，而同位語從句中的that是連詞隆豹，只起連接主句與從句的作用，不充當(dāng)句中任何成分茅逮。
(2) 定語從句是形容詞性的璃赡，其功能是修飾先行詞，對先行詞加以限定献雅，描述定的性質(zhì)或特征;同位語從句是名詞性的鉴吹，其功能是對名詞進行補充說明。例如：
1) The news that he told me is that Tom would go abroad next year.(他告訴我的消息是湯姆明年將出國惩琉。)(第一個that引導(dǎo)的從句是定語從句，that在從句中作賓語)
2)The news that Tom would go abroad is told by him.(湯姆將出國的消息是他講的夺荒。)(同位語從句瞒渠，that在句中不作任何成分) 。
