which與as在定語從句中的不同用法

　　(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(dòng)詞be的主語，也可以作實(shí)義動(dòng)詞的主語，而這時(shí)as 只可以做系動(dòng)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(dòng)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(shí)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。