非限定性定語從句as

導語：非限定性定語從句，非限定性定語從句的作用是對所修飾的成分作進一步說明，通常和主句間用逗號隔開，將從句拿掉後其他部分仍可成立。下面是小編給大家整理的非限定性定語從句as的相關內容，希望能給你帶來幫助!

　（一）非限定性定語從句as引導

as引出非限定性定語從句時，代替整個主句，對其進行說明但通常用於像as we all know, as it is known, as is known to all, as it is, as is said above, as always mentioned above, as is usual, as is often the case, as is reported in the newspaper等句式中。as在非限定性定語從句中作主語、表語或賓語，且引出的從句位置比較靈活，可位於句首或句末，也可置於主句中間。通常均由逗號將其與主句隔開。as有“正如……， 就像……”之意。

如：As is known to the United States, Mark Twain is a great American writer.

美國人都知道，馬克·吐溫是一位偉大的美國作家。（as在從句中作主語）

He forgot to bring his pen with him, as was often the case.

他忘了帶筆，這是常事。（as在從句中作主語）

He is absorbed in work, as he often was.

他正在全神貫注地工作，他過去經常這樣。（as在從句中作表語）

As we all know, the earth is round.

眾所周知，地球是圓的。（as在從句中作賓語）

The two brothers were satisfied with this decision，as was agreed beforehand.

兩兄弟對此決定都滿意，這項決定在事前都已得到他們的同意。(as在從句中作主語)

Taiwan is，as you know，an inseparable part of China.

你知道，臺灣是中國不可分割的一部分。(as在從句中作賓語)

“介詞+關係代詞”引導非限制性定語從句：在介詞後引導非限制性定語從句。

難：句意相同

as it is known to all (that...) (as 做狀語從句連詞，是狀語從句, 可以加that)

與 as is known to all (as做主語，是定語從句)

與 it is known to all that... (主語從句，it是形式主語)

即：As is widely known, the moon is closer to the us than the sun.(定從)

= That the moon is closer to the us than the sun is widely known.(主從)

= It is widely known that the moon is closer to the us than the sun.(主從)

As it is known to everyone, I thought you knew about it too.(狀從)[1]

關係代詞which有時並不代表主句中某一確定的詞，而是概括整個主句的意思。介詞的`選擇取決於它與先行詞的搭配或與從句中謂語動詞的搭配。

They were short of sticks to make frames for the climbing vines，without which the yield would be halved.

他們缺搭葡萄架的杆兒，沒有它們產量會減少一半。

They thanked Tom，without whose support they would not have succeeded.

他們很感激Tom，沒有他的支援他們是不會成功的。

（二）as, which 非限定性定語從句

由as, which 引導的非限定性定語從句，as和which可代整個主句，相當於and this或and that，as, which 非限定性定語從句。As一般放在句首，which在句中。

As we know, smoking is harmful to one's health.

The sun heats the earth, which is very important to us.

典型例題

1）Alice received an invitation from her boss, ___came as a surprise.

A. it B. that C. which D. he

答案C. 此為非限定性從句，不能用 that修飾，而用which.，it 和he 都使後句成為句子，兩個獨立的句子不能單以逗號連線。況且選he句意不通。

2）The weather turned out to be very good, ___ was more than we could expect.

A. what B. which C. that D. it

答案B。which可代替句子，用於非限定性定語從句，而what不可。That 不能用於非限定性定語從句，it不為連詞，使由逗號連線的兩個句子並在一起在英語語法上行不通，英語語法《as, which 非限定性定語從句》。

3）It rained hard yesterday, ____ prevented me from going to the park..

A. that B. which C. as D. it

答案B.

as 和which在引導非限制性定語從句時，這兩個關係代詞都指主句所表達的整個意思，且在定語從句中都可以作主語和賓語。但不同之處主要有兩點：

(1） as 引導的定語從句可置於句首，而which不可。

(2） as 代表前面的整個主句並在從句中作主語時，從句中的謂語必須是系動詞；若為行為動詞，則從句中的關係代詞只能用which.。

在本題中，prevent由於是行為動詞，所以正確選項應為B。

As 的用法

例1. the same… as；such…as 中的as 是一種固定結構, 和……一樣……。

I have got into the same trouble as he (has).

例2. as可引導非限制性從句，常帶有'正如'。

As we know, smoking is harmful to one's health.

As is know, smoking is harmful to one's health.

As是關係代詞。例1中的as作know的賓語；例2中，它充當從句的主語，謂語動詞know要用被動式。