限定性定語從句,顧名思義,是對先行詞從本質或特征上進行限制的一種定語從句,它所修飾的詞代表一個(些)或一類特定的人或事、物.例如:
A man who doesn't learn from others can't achieve much.一個不向別人學習的人是不能有多少成就的.
A man被限定后,指一類特定的人.這類定語從句是不能去掉的,否則剩下的部分就失去意義不能成立,或者含義不清,甚至讓人感到莫名其妙.非限定性定語從句則不然,它只對所修飾的詞作進一步的說明,去掉之后并不影響句子的整個含義.在形式上,非限定性定語從句與主句之間通常用逗號隔開.例如:
Finally we visited to the Giant Yangtze Gorges Dam,which is the greatest key water control project in the world at present.最后我們參觀了長江三峽大壩,它是目前世界上最大的水利樞紐工程.
本句若去掉從句,主句部分的含義仍然完整.歷年的高考中,非限定性定語從句都是出現頻率最高的考點之一.因此值得我們注意.
二、引導非限定性定語從句時,只能用which(不用that).例如:
Heat is another form of energy,which is as important as other kinds of energy.熱是另一種形式的能量,與其他形式的能量一樣重要.
從句表補充說明,而且關系代詞which不能換成that.
三、引導非限定性定語從句的which可以指代前面的先行詞,也可以指前面整個句子的含義.例如:
That Peter will marry Alice,which has not been announced yet,has spread around.彼特要娶愛麗斯這件事還沒宣布,卻已傳得沸沸揚揚.
句子中的which指"彼特要娶愛麗斯"這整個句子的意思.
四、除which外,還可用when,where,who等關系代、副詞引導非限定性定語從句.例如:
After graduation,I decided to stay in Chongqing,where I spent my childhood and four years of college life.畢業(yè)后,我決定留在重慶,在那里我曾度過了我的童年和四年大學生活.
Albert Einstein left Germany for the United States during World War II,when Jews were badly treated in Germany.第二次世界大戰(zhàn)期間,愛因斯坦離開德國去了美國,那時猶太人在德國受到不好的對待.
五、在限定性定語從句中作賓語時,引導詞可以省略,但引導非限定性定語從句的關聯(lián)詞不能省.試比較:
He was eager to go to the hospital to see his stepmother,whom he loved and respected as his own mother.他急于想去醫(yī)院看望他的繼母,他把他的繼母當作親生母親一樣熱愛和尊敬.
The American journalist (whom / who) the announcer mentioned in the news broadcast is said to have been killed by the gangsters.播音員在新聞廣播中提到的那位美國記者據說已經被匪徒殺害了.
兩例中的關系代詞都在從句中作賓語.由于第二例是限定性定語從句,可以省略關系代詞;第一例中的引導詞不能省略,因為它引導的是非限定性定語從句.
六、表示"正如"的含義時,通常用as引導非限定性定語從句,也可用which引導;但置于句首時,只能用as引導.
例如:
China has basically succeeded in defeating SARS,which / as we have expected.正如我們所預料的那樣,中國已基本上戰(zhàn)勝了"非典".
As is well known to everybody,Taiwan is an inseparable part of China.眾所周知,臺灣是中國不可分割的一部分.
但是當非限定性定語從句是否定含義時,就只能用which(而不用as)引導.例如:
He didn't win the championship,which I hadn't expected.他沒獲得冠軍,這一點是我沒預料到的.