非限定性定語(yǔ)從句起補(bǔ)充說(shuō)明作用，在句子中不充當(dāng)成分，缺少也不會(huì)影響全句的理解，它與主句往往用逗號(hào)隔開(kāi)。定語(yǔ)從句有限制性和非限制性?xún)煞N。

限制性定語(yǔ)從句是先行詞不可缺少的部分，去掉它主句意思往往不明確;非限制性定語(yǔ)從句是先行詞的附加說(shuō)明，去掉了也不會(huì)影響主句的意思，它與主句之間通常用逗號(hào)分開(kāi)，將非限定性定語(yǔ)從句放在句子中間，其前后都需要用逗號(hào)隔開(kāi)。

非限定性定語(yǔ)從句的分類(lèi)

who引導(dǎo)

Our guide，who was a French Canadian，was an excellent cook.

我們的向?qū)?，一個(gè)法裔加拿大人，是一位優(yōu)秀的廚師。

My gardener，who is very pessimistic，says that there will be no apples this year.

我家的園丁非常悲觀，他說(shuō)今年將不結(jié)蘋(píng)果。

whom引導(dǎo)

關(guān)系代詞whom用于指人，在句中作動(dòng)詞賓語(yǔ)和介詞賓語(yǔ)，作介詞賓語(yǔ)時(shí)，介詞可位于句首。

如:Peter, whom you met in London, is now back in Paris.

彼得現(xiàn)在回巴黎了，你在倫敦見(jiàn)過(guò)他。

Mr Smith，from whom I have learned a lot，is a famous scientist.

史密斯先生是一位著名的科學(xué)家，我從他那兒學(xué)了許多東西。

whose引導(dǎo)

whose是關(guān)系代詞who的所有格形式，在從句中作定語(yǔ)。whose通常指人，也可指動(dòng)物或無(wú)生命的事物。

如:The boy,whose father is an engineer, studies very hard.

這個(gè)男孩，他的爸爸是一位工程師，學(xué)習(xí)很努力

Above the trees are the mountains, whose magnificence the river faithfully reflects on the surface.

在樹(shù)林的高處是山，其壯麗的景色完全映照在河面上。

The play，whose style is rigidly formal，is typical of the period.

這劇本是那個(gè)時(shí)期的典型作品，風(fēng)格拘謹(jǐn)刻板。

which引導(dǎo)

關(guān)系代詞which在非限制性定語(yǔ)從句，中所指代和修飾的可以是主句中的名詞、形容詞、短語(yǔ)、其他從句或整個(gè)主句，在從句中作主語(yǔ)、動(dòng)詞賓語(yǔ)、介詞賓語(yǔ)或表語(yǔ)。

①which指代主句中的名詞，被指代的名詞包括表示物、嬰兒或動(dòng)物的名詞、表示單數(shù)意義的集體名詞以及表示職業(yè)、品格等的名詞。

如:These apple trees，which I planted three years ago，have not borne any fruit.

這些蘋(píng)果樹(shù)是我三年前栽的，還沒(méi)有結(jié)過(guò)果實(shí)。

She is an artist，which I am not.

她是一位藝術(shù)家，而我不是。

Water，which is a clear liquid，has many uses.

水是一種清澈的液體，有許多用途。

The two policemen were completely trusted，which in fact they were.

那兩個(gè)警察完全受到信任，事實(shí)上也確實(shí)如此。

②which指代主句中的形容詞。

如:She was very patient towards the children，which her husband seldom was.

她對(duì)孩子們很耐心，她丈夫卻很少這樣。

She is always careless，which we should not be.

她總是馬虎大意，我們可不應(yīng)該這樣。

③which指代主句中的某個(gè)從句。

如:He said that he had never seen her before，which was not true.

他說(shuō)以前從沒(méi)見(jiàn)過(guò)她，這不是真的。

④which指代整個(gè)主句。

如:In the presence of so many people he was little tense, which was understandable.

在那么多人面前他有點(diǎn)緊張，這是可以理解的。

He may have acute appendicitis，in which case he will have to be operated on.

他可能得了急性盲腸炎，如果是這樣，他就得動(dòng)手術(shù)。

When deeply absorbed in work，which he often was，he would forget all about eating and sleeping.

他經(jīng)常聚精會(huì)神地工作，這時(shí)他會(huì)廢寢忘食。

when引導(dǎo)

關(guān)系副詞when在非限制性定語(yǔ)從句中作時(shí)間狀語(yǔ)，指代主句中表示時(shí)間的詞語(yǔ)。

如:He will put off the picnic until May 1st, when he will be free.

他將把郊游推遲到5月1號(hào)，那時(shí)他將有空。

where引導(dǎo)

副詞where在非限制性定語(yǔ)從句中作地點(diǎn)狀語(yǔ)，指代主句中表示地點(diǎn)的詞語(yǔ)。

如:They went to London，where they lived for six months.

他們?nèi)チ藗惗?，在那兒呆了六個(gè)月的時(shí)間。

as引導(dǎo)

as引出非限定性定語(yǔ)從句時(shí)，代替整個(gè)主句，對(duì)其進(jìn)行說(shuō)明但通常用于像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(yǔ)從句中作主語(yǔ)、賓語(yǔ)，且引出的從句位置比較靈活，可位于句首或句末，也可置于主句中間。通常均由逗號(hào)將其與主句隔開(kāi)。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(guó)人都知道，馬克·吐溫是一位偉大的美國(guó)作家。(as在從句中作主語(yǔ))

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(yǔ)）

He is absorbed in work, as he often was.

他正在全神貫注地工作，他過(guò)去經(jīng)常這樣。(as在從句中作表語(yǔ))

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(yǔ))

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

兩兄弟對(duì)此決定都滿(mǎn)意，這項(xiàng)決定在事前都已得到他們的同意。(as在從句中作主語(yǔ))

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

你知道，臺(tái)灣是中國(guó)不可分割的一部分。(as在從句中作賓語(yǔ))

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

與 as is known to all(as做主語(yǔ)，是定語(yǔ)從句)

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

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)

關(guān)系代詞which有時(shí)并不代表主句中某一確定的詞，而是概括整個(gè)主句的意思。介詞的選擇取決于它與先行詞的搭配或與從句中謂語(yǔ)動(dòng)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?nèi)贝钇咸鸭艿臈U兒，沒(méi)有它們產(chǎn)量會(huì)減少一半。

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

他們很感激Tom，沒(méi)有他的支持他們是不會(huì)成功的。

"介詞+關(guān)系代詞"引導(dǎo)非限制性定語(yǔ)從句:在介詞后引導(dǎo)非限制性定語(yǔ)從句。

非限定性定語(yǔ)從句的特殊結(jié)構(gòu)

"名詞/代詞+of+which/whom/who "

It now has 20，000 hectares of land，more than two-thirds of which are under cultivation.

現(xiàn)在它擁有兩萬(wàn)公頃土地，其中三分之二之多已經(jīng)耕種。

Light is the fast thing in the world, the speed of which is 300000 kilometer per second.

光是世界上最快的東西，它的速度是每秒30萬(wàn)千米。

There are 30 chairs in the small hall, most of which are new.

大廳里有三十把椅子，絕大部分是新的。

The textile mill has over 8，000 workers and staffs，eighty per cent of who are women.

這家紡織廠有8千多職工，女職工占百分之八十。