as引導限制性定語從句

在非限制性從句中，which後的be動詞不可省；as而後的be動詞可以省略。以下內容是小編為您精心整理的as引導限制性定語從句，歡迎參考！

　　as引導限制性定語從句一

一、相同點

兩者引導非限制性定語從句時，可指代主句中的部分或整個句子的內容，在從句中做主語，賓語或表語，位於主句之後有時可互換。

The meeting was put off, as /which was exactly what we wanted.

He was a doctor, as/which I knew from his manner.

二、不同點

1. as可以放在主句前後，也可插入主句之中；而which引導的非限制性從句只能位於主句之後。

As is known to all, fish can’t live without water.

Air, as we know, is gas.

2.在非限制性從句中，which後的be動詞不可省；as而後的be動詞可以省略。

She told me she won the match, which was a lie.

The material is elastic, as (was) shown in the figure.

3. which在非限制性定語從句做主語時可用各類動詞做謂語；而as做主語時，謂語常用系動詞，如be, seem, become等，一般不用其他行為動詞。

He saw the girl, which delighted him.

He didn’t say anything at the meeting , as/which seemed very strange.

4. as常用“正如”含義，常用的結構有as we know（眾所周知）；as often happens（正如常發生的那樣）；as is often the case（情況常常如此）; as we all can see（正如我們看到的`）; be announced/expected/known/imagined/mentioned/said/shown/

reported等。這些結構常放句首，偶爾也可以放句中或句末。

As is known to all, China is a developing country.

Kate was late for school, as often happened.

5. 在非限制性定語從句中which指代主句中某一個單詞時，as不可以。

My brother enjoyed playing basketball, which he really plays well.

Beijing, which he was born in, is our capital.

6. “介詞+關係代詞（介賓代物）”中關係代詞只能用which。

The Travel Agency, with which our company has been dealing for several years, has opened for new branches.

Air is a mixture of gases, of which oxygen forms 21 percent.

7. 從句中的謂語動詞是否定形式時，常用which。

He can write a letter in English, which I can not.

Metal will bear beating with a hammer, which a stone will not

8.在非限制性定語從句關係代詞代表前面主句中的賓語從句時，常用which

He said he had passed the exam, which was untrue.

　　as引導限制性定語從句二

1. as引導限制性定語從句的主要結構有：the same…as；as…as；such…as；so…as。主句中出現the same, as, such, so修飾先行詞，需選擇as做關係代詞在定語從句中做主語或賓語。例，It’s the same person as we wanted to find yesterday .

2、as引導非限制性定語從句，指代整個主句內容，從句可置於句首，句中或句尾。

例：As everyone knows ,China is a beautiful country with a long history .

3、非限制性定語從句中的謂語為被動式時，常用as做主語。

例：besaid/known/announced/reported/mentioned/expected/discussed