各種從句的語法總結
導語：高級的英語語法知識比初級英語的要難得多，下面YJBYS小編分享高級英語的重要語法，歡迎學習!
虛擬語氣在各種從句的應用
主語從句的虛擬
1. It is + adj. + that sb. (should) do
常見的形容詞有：necessary, important, strange, natural
It's important that he take my advice.
2. It is + n. + that sb. (should) do
常見的名詞有：a pity, a shame, no wonder, one's wish
It's a pity that he be so silly.
3. It is + done + that sb. (should) do
常見的過去分詞有：suggested, advised, demanded, requested, required, asked, ordered,
proposed, decided, desired, insisted等。
It's requested that she go home as soon as possible.
賓語從句的虛擬
1. 表命令，表建議，表要求的動詞，后接賓語從句虛擬。虛擬的構成為(should) do。
I advise that he stay at home.
2. wish后接從句，虛擬的構成是往過去推一個時態。
I wish I had watched the football match last night.
注意以下幾組詞或短語用于虛擬語氣中。
1. as if, as though
He speaks English as if he were a native speaker.
2. otherwise, but, even though
He was ill. Otherwise he would have been there.
3. with, without, but for
Without your help, I would have died two years ago.
But for your help, I would have died two years ago.
4. would rather I'd rather you told me yourself.
5. It's time that
It's time that you went to bed.
It's time that you should go to bed.
表語從句中的虛擬
在表語從句中，表示間接的命令，要求、請求、建議、決定等，主句中的主語通常是suggestion, proposal, request, orders, idea等。從句謂語形式是"(should)+動詞原形"。如：
His suggestion is that we (should) leave at once.
名詞從句部分：
1. that不可省略的情況
2. that引導同位語從句和that引導定語從句的區別：同位語從句中的that是連詞，不做成分，只連接主從句，不能省略;定語從句中的that要代替先行詞在從句中做主語、賓語或者表語，并且做賓語時可以省略。從語義上看，同位語從句是對前面名詞的解釋、說明或內容;而定語從句時對前面名詞的限定。
We should consider the students’request that the school library provide more books on
popular science. (that引導同位語從句)
The only hope that he expressed was that they would do what they could to help the people
in disaster areas. (that引導定語從句)
3. 要根據句子結構尤其是謂語動詞判斷從句的類型：
What is known to us all is that the 2008 Olympic Games took place in Beijing.
本句含有一個主語從句和一個表語從句，主句的動詞為is。
It is known to us all that the 2008 Olympic Games took place in Beijing.
本句含有一個主語從句，主句的動詞為is known to。
As is known to us all, the 2008 Olympic Games took place in Beijing.
本句含有一個定語從句，主句的動詞為took place，as引導非限制性定語從句。
4. 名詞性從句的語序和語態。
名詞性從句均應用陳述語序，不能用疑問語序，其時態應該和主句時態保持一致。
5. 名詞性從句中連詞的省略。
介詞后的連詞以及引導主語從句和同位語從句的連詞不可省略。that引導名詞從句(除了引導第一個賓語從句可省略外)都不可省略，但是引導定語從句并在從句中做賓語時可以省略。 that不能省略的情況：1)介詞后面的that不能省略：
Peter is a good student except that he is sometimes careless.
2)當that引導的賓語從句位于句首時：
That he ever did such a thing I don’t believe.
3)主句謂語動詞和that從句之間有插入語，that不省略：
She said that, if she failed, she would try again.
4)當賓語從句有其他從屬連詞時，that不省略：
He told me that if it was necessary they would work extra time.
6.名詞性從句中it的使用：
為了保持句子平衡，多數情況下，it作形式主語或形式賓語，將真正的主語或賓語從句后置。 定語從句關系代詞有who, whom, whose, which, that, as,和關系副詞when, where, why。
(1)that指物時一般可與which互換，但在下列情況下，要用that而不用which。
a. 先行詞有all, everything等不定代詞時，如，
Everything (that) he did is wrong.
b. 先行詞被all, every, no, some, any, little, much等修飾時，如，
I'll read all the books (that) you lend me.
c. 先行詞被序數詞或形容詞最高級修飾時，
This is the first letter (that) the boy has written.
d. 先行詞被the only, the very, the same, the last修飾時，如
He is the very man (that) I'm looking for.
e. 只用which的情況
在介詞后或在非限定性定語從句中
This is the book about which we have talked a lot.
The book, which he gave me yesterday, is very interesting.
f. where和when作關系副詞
This is the room where I worked.
This is the room which I stayed in.
I remembered the day when we lived there.
I remembered the day that I spent there.
g. as和which
as 可以放于句首，而which 不可以
As you know, he is good at English.
three of them 和three of which
I have a lot of books, three of which are in Russian.
I have a lot of books and three of them are in Russian.
(2. )“介詞+關系代詞”的情況：
在固定短語中介詞不能提前;判斷介詞的口訣：瞻前顧后看意義
瞻前——看先行詞;顧后——找從句動詞;看意義——看全句表達含義
(3. )先行詞在從句中充當地點狀語時，關系詞用where 或者介詞加which;先行詞在從句中充當時間狀語時，關系詞用when或者介詞加which;先行詞在從句中充當原因狀語時，關系詞用why或者for which。
(4. )注意as和which在非限制性定語從句中代表主句所表達的內容的區別：
位置不同：as從句放在主句前或后均可;而which從句只能放在主句后
作用不同：as從句動詞常常是see \know等，因而相當于插入語;which從句則在陳述一件事實。
狀語從句部分
1.while 是高考中的高頻詞，它既可引導時間狀語從句，又可引導并列句，還可引導讓步狀語從句，表示“盡管”。
2. no matter wh- 與wh-ever 的聯系及區別：no matter wh- 只引導讓步狀語從句，此時與wh-ever通用。wh-ever又可引導名詞性從句，No matter wh-不能。
No matter when / Whenever he comes back, he should be invited to the party.
3. 在條件，時間和讓步從句中，用一般現在時表示一般將來時，用現在完成時表將來完成時，
用一般過去時表過去將來時。在since 引導的時間狀語從句中，動詞一般都用一般過去時，而主句常用現在完成時。
4. 狀語從句的倒裝一般有下面幾種情況：①否定詞開頭;②so 加adj. 開頭;③as /
though引導的讓步狀語從句。
5. 連詞before小結：
We had sailed four days before we saw land. (……才)
We hadn’t run a mile before he felt tired. (不到……就)
Please write it down before you forget it. (趁……)
Before I could get in a word, he had measured me. (還沒來得及)
It will be/was…before…要過多久才……
6. because, since, as 引導原因從句的區別：because表達直接原因，語氣最強，回答why;
since通常放句首，譯為“既然”;as引導不談自明的原因，語氣最弱;
7. as可以引導多種從句，要注意其中的區別。
8. till, until和not…until的區別;if和unless的區別
非謂語動詞部分動詞不定式幾點注意。
1.下列動詞或動詞短語后接不定式：agree, seem, appear, offer, happen, wish, hope, pay,
expect, long, plan, intend, promise, pretend, decide, afford, manage, choose, be said to,would like to等。
2. 不定式常用的句型：too…to do (太……而不能), …enough to do…(夠……就能……), so as to do/in order to do(為了……)，so…as to do/such…as to do(如此……結果……)。
3. 不定式的三個結構：即否定結構、復合結構和疑問結構。
否定結構為“not (never) to do”;疑問結構是特殊疑問詞“how (what, which, who, whether…) to do”;復合結構是“for/ of +名詞(或代詞賓格)+ to do ”。
4. let/ make/ have/ see/ hear/ notice/ observe/ listen to/ look at/ watch/feel
這些動詞帶不定式作賓補時，省掉to, 若這些動詞以被動形式出現時，應加上to。
5. 當前面是the first, the second, the last, need, plan, time, chance, right,determination,ability, opportunity(機會)，way時，一般用不定式作定語。
6. but/ except + to do/ do 結構，要根據謂語動詞來確定其后面的形式。當謂語動詞是do,does, did時，but后用動詞原形;謂語動詞是其他動詞時，but后用“to + 動詞原形”的形式。
7. 形容詞后一般用不定式(除busy, worth 兩個外)。
You are sure to succeed. 你一定能成功。
He is busy preparing his lessons at present. 他現在正忙于預習功課。
8. 不定式作定語和表語時，有時需要在后面放上一個適當的介詞。
This is a bench to sit on.(這是用來坐的凳子。)
This room is comfortable to live in. (這個房間住起來很舒適。)
9. 在“主語+系動詞+adj.+不定式”這個句型中，當主語是不定式的邏輯賓語時，不定式不用被動，不能在動詞后再放賓語。
The question is easy to answer. (question是answer的賓語，不能說：The question is easy to be answered. 也不能說：The question is easy to answer it .)
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