as作定語從句

　　as和which都能引導(dǎo)定語從句,并都可以在定語從句中做主語或賓語,代表前面整個(gè)句子.以下是小編為大家整理分享的as作定語從句，歡迎閱讀參考。

　　as作定語從句

　　透析which與as在定語從句中的運(yùn)用

　　定語從句是高中英語的主要語法項(xiàng)目之一,也是高考英語的常考知識點(diǎn),尤其是as和which引導(dǎo)的定語從句,更是歷年高考試題中的重點(diǎn)和熱點(diǎn).as和which在引導(dǎo)定語從句時(shí)既有相同點(diǎn)又存在著很大的區(qū)別.

　　一、相同點(diǎn)

　　1. as和which都能引導(dǎo)定語從句,并都可以在定語從句中做主語或賓語,代表前面整個(gè)句子.

　　例 1 He married her, as / which was natural. 他跟她結(jié)婚了,這是很自然的事.

　　例 2 He is honest, as we can see. 他很誠實(shí), 這一點(diǎn)我們看得出來.(表示人們從日常主觀常識, 經(jīng)驗(yàn)對某一事情的看法、評價(jià),用as為妥.)

　　2. 當(dāng)非限定性定語從句置于句末時(shí),as和which都可用來引導(dǎo)這個(gè)定語從句.

　　例 3 The number of senior high school students is increasing, as is mentioned above. （as引導(dǎo)非限定性定語從句,意思是“正如”.此時(shí)也可以換用which引導(dǎo),但意思有別,意思是：“這一點(diǎn)上面提到了”.）

　　二、不同點(diǎn)

　�。ㄒ唬┱Z義上的區(qū)別

　　as作為關(guān)系代詞仍多少保留 “理由”“比較” “方式” “等同”等意義,而which沒有這些意義.因此,由as引導(dǎo)的定語從句通常在意義上不可與主句相悖,而且一般是肯定的,對主句意義起相輔作用,表示 “正如”等意義；而which引導(dǎo)從句則不受此限制.

　　例 4 Mother treats me just like a baby,which I can’t bear． 媽媽對我就像小孩,我真受不了.

　　例 5 She has married again,which was unexpected． 她又結(jié)婚了,這是大家沒有預(yù)料到的.

　　上面兩句中的which都不宜用as.

　　但當(dāng)否定的定語從句作正面理解,對主句起相輔作用而不是與其相悖時(shí),仍可用as.

　　例 6 He turned his eyes on Philip’s face,as he had not done for ten years．他轉(zhuǎn)過身來看著菲利普的臉,他十年來沒有這樣看過他的臉了.

　　例 7 He really can’t lend you the money,as you might not realize． 他的確不能把那些錢借給你,這一點(diǎn)你可能意識不到.

　�。ǘ�）用法上的區(qū)別

　　1. which與as引導(dǎo)非限制性定語從句的區(qū)別：

　　（1）which只能放在主句后面,而as引導(dǎo)的從句位置相對比較靈活,可以放在前,也可以放在后,甚至還可以分割主句.另外,as 常常有“正如、正像”的含義.

　　例 8 As he realized, I was very useful to him.（在前）

　　例 9 Air, as we know, is a gas. （在中）

　　例 10 He was a foreigner, as I know from his accent. (在后)

　　例 11 He came late again, which made his boss angry.（在后）

　　例 12 As is known to all, China is a developing country. 眾所周知,中國是發(fā)展中國家.

　�。�2）在which引導(dǎo)的.定語從句中,謂語動詞若是am, is, are,則這些系動詞不能省略,而as后面若是這種情況,則可以省略.

　　例 13 He is a teacher, as (is) clear from his manner. (is可以省略)

　　例 14 He said he had never seen her before, which was not true. （was 不可省略）

　　（3）當(dāng)which引導(dǎo)的從句在意義上近乎并列關(guān)系時(shí),可以用and this, and that代替,意思是“這件事”.

　　例 15 He changed his mind, which(and this, and that) made me very angry. 他改變了主意,這使我很生氣.

　　而as主要起與上下文連接的作用,表達(dá)說話人的看法、觀點(diǎn),并指出主句內(nèi)容的出處或根據(jù)等.

　　例 16 Einstein, as we know, is a famous scientist.愛因斯坦,眾所周知,是一位偉大的科學(xué)家.

　　例 17 As is announced in today’s newspaper, we must improve our style of work. 今天的報(bào)紙上說,我們必須改進(jìn)工作作風(fēng).

　�。�4）做主語時(shí),which既可以作系動詞be的主語,也可以作實(shí)義動詞的主語,而這時(shí)as 只可以做系動詞be的主語.

　　例 18 He married her, which was natural. （可用as代替which）他和她結(jié)婚,這是很自然的事.

　　例 19 He won a /the Nobel Prize in chemistry, which made him illustrious. (不可用as代替which)他獲得了諾貝爾化學(xué)獎(jiǎng),這使他名揚(yáng)天下.

　　（5）當(dāng)定語從句位于主句之后,純粹表示主句所述的內(nèi)容,不帶有“如……那樣”的意思時(shí),往往用which, 而不用as.

　　例 20 They were invited to the state banquet, which(as) was a great honor to them. 他們被邀請參加國宴,這對他們來說是莫大的榮幸.

　　例 21 We had to sleep in our wet clothes, which was most uncomfortable. 我們不得不穿著濕衣服睡覺,這簡直太不舒服了.

　�。�6）當(dāng)定語從句有“如同……那樣”的含義時(shí),用as比用which更常見,而這些從句幾乎成為固定說法.

　　例 22 Things will turn out contrary to one’s wishes, as is often the case. 事與愿違,這是常有的事.

　　例 23 As was natural, this inordinate hope was followed by an excessive depression.這種過分希望之后,接著是極度的沮喪,是很自然的事.

　　例 24 The material is elastic, as is show in the figure. 這種材料有彈性,如圖所示.

　　例 25 As we know. 眾所周知.

　　例 26 As has been said above/ before. 正如前文所述 .

　�。�7）當(dāng)定語從句的關(guān)系代詞指的是先行詞本身時(shí),只能用which.

　　例 27 These apple trees, which I planted tree years ago, have not borne any fruit.這些蘋果樹是我三年前種下的,沒結(jié)出任何果實(shí).

　　例 28 The Thames, which is now clean enough to swim in, was polluted for over a hundred years.泰晤士河,現(xiàn)在已經(jīng)很干凈,可以在里面游泳,它曾被污染了一百多年.

　　（8）帶介詞的典型的定語從句,必須用which,不能用as.

　　例 29 There is a great deal of oxygen around us, without which we could not live. 我們周圍有許多氧氣,沒有它我們就無法生存.

　　例 30 The shed in our garden, in which we often played, has lasted for a long time. 我們經(jīng)常玩耍的花園里的那個(gè)棚子,已經(jīng)有很長時(shí)間了.

　�。�9）as常與從句中的know,see, hear,expect等動詞連用,也常用于as often happens,as is often the case（常有的事）等句子中；而which一般不用于以上情況.

　　例 31 As is well known,Shanghai is a big city．

　�。�10）當(dāng)后置的非限制性定語從句是否定結(jié)構(gòu)時(shí),只能用which引導(dǎo).

　　例 32 The result of the experiment was very good, which we hadn’t expected.

　　2. 引導(dǎo)限制性定語從句時(shí)which與as的區(qū)別：

　　(1)先行詞如果是表示物的名詞或代詞,在從句中又做介詞的賓語時(shí),只能用which.

　　例 33 This is the pan in which I boiled the milk. 這就是我煮牛奶的鍋.

　�。�2）前面有as時(shí),引導(dǎo)定語從句的關(guān)系代詞用as, 不用which.

　　例 34 There are as many dictionaries as are needed.所需要的字典都有了.

　�。�3）前面有such時(shí),引導(dǎo)的定語從句的關(guān)系代詞用as, 不用which.

　　例 35 Such women as know Tom thought he was charming. 認(rèn)識湯姆的女人都認(rèn)為他很迷人.

　　例 36 I have never heard such stories as he tells. 他講的那些故事我從沒聽過.

　�。�4）前面有the same時(shí),引導(dǎo)定語從句的關(guān)系代詞用as而不用which.

　　例 37 We are facing the same problems as we did years ago.我們正面臨著和多年以前同樣的困難.

　　例 38 This is the same wallet as I lost. 這只錢包與我丟失的那只相同.

　�。�5）單個(gè)詞引導(dǎo)限制性定語從句時(shí),一般不用as而用which和that.由于關(guān)系詞在從句中作賓語,which和that都可以省略.

　　例 39 The project which/that a British businessman has invested in is under construction at present.

　�。�6）“介詞+關(guān)系代詞”引導(dǎo)定語從句時(shí),只能用which.

　　例 40 Recently I bought an ancient Chinese vase, the price of which was very reasonable.

　　注：此時(shí)的which不能用as來代替.另外還應(yīng)注意：引導(dǎo)定語從句時(shí),which不能單獨(dú)作定語,此時(shí)不管先行詞是人還是物,都只能用whose引導(dǎo),但指物時(shí),可以用of which替換.

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