which与as在定语从句中的不同用法

下面是小编整理的一些关于which与as在定语从句中的用法，希望帮助大家区分这两个单词。提高英语水平。

　　一、which与as用法相同点

1. as和which都能引导定语从句，并都可以在定语从句中做主语或宾语，代表前面整个句子。

例 1 He married her, as / which was natural. 他跟她结婚了，这是很自然的事。

例 2 He is honest, as we can see. 他很诚实， 这一点我们看得出来。(表示人们从日常主观常识, 经验对某一事情的看法、评价,用as为妥。)

2. 当非限定性定语从句置于句末时，as和which都可用来引导这个定语从句。

例 3 The number of senior high school students is increasing, as is mentioned above. (as引导非限定性定语从句，意思是“正如”。此时也可以换用which引导，但意思有别，意思是：“这一点上面提到了”。)

　　二、which与as用法不同点

(一)语义上的区别

as作为关系代词仍多少保留 “理由”“比较” “方式” “等同”等意义，而which没有这些意义。因此，由as引导的定语从句通常在意义上不可与主句相悖，而且一般是肯定的，对主句意义起相辅作用，表示 “正如”等意义;而which引导从句则不受此限制。

例 4 Mother treats me just like a baby，which I can’t bear. 妈妈对我就像小孩，我真受不了。

例 5 She has married again，which was unexpected. 她又结婚了，这是大家没有预料到的。

上面两句中的which都不宜用as。

但当否定的定语从句作正面理解，对主句起相辅作用而不是与其相悖时，仍可用as。

例 6 He turned his eyes on Philip’s face，as he had not done for ten years.他转过身来看着菲利普的脸，他十年来没有这样看过他的脸了。

例 7 He really can’t lend you the money，as you might not realize. 他的确不能把那些钱借给你，这一点你可能意识不到。

(二)用法上的区别

1. which与as引导非限制性定语从句的区别：

(1)which只能放在主句后面，而as引导的从句位置相对比较灵活，可以放在前，也可以放在后，甚至还可以分割主句。另外，as 常常有“正如、正像”的含义。

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. 众所周知，中国是发展中国家。

(2)在which引导的定语从句中，谓语动词若是am, is, are，则这些系动词不能省略，而as后面若是这种情况，则可以省略。

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)当which引导的从句在意义上近乎并列关系时，可以用and this, and that代替，意思是“这件事”。

例 15 He changed his mind, which(and this, and that) made me very angry. 他改变了主意，这使我很生气。

而as主要起与上下文连接的作用，表达说话人的看法、观点，并指出主句内容的出处或根据等。

例 16 Einstein, as we know, is a famous scientist.爱因斯坦，众所周知，是一位伟大的科学家。

例 17 As is announced in today’s newspaper, we must improve our style of work. 今天的报纸上说，我们必须改进工作作风。

(4)做主语时，which既可以作系动词be的主语，也可以作实义动词的主语，而这时as 只可以做系动词be的主语。

例 18 He married her, which was natural. (可用as代替which)他和她结婚，这是很自然的事。

例 19 He won a /the Nobel Prize in chemistry, which made him illustrious. (不可用as代替which)他获得了诺贝尔化学奖，这使他名扬天下。

(5)当定语从句位于主句之后，纯粹表示主句所述的内容，不带有“如……那样”的意思时，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. 他们被邀请参加国宴，这对他们来说是莫大的荣幸。

例 21 We had to sleep in our wet clothes, which was most uncomfortable. 我们不得不穿着湿衣服睡觉，这简直太不舒服了。

(6)当定语从句有“如同……那样”的含义时，用as比用which更常见，而这些从句几乎成为固定说法。

例 22 Things will turn out contrary to one’s wishes, as is often the case. 事与愿违，这是常有的事。

例 23 As was natural, this inordinate hope was followed by an excessive depression.这种过分希望之后，接着是极度的沮丧，是很自然的事。

例 24 The material is elastic, as is show in the figure. 这种材料有弹性，如图所示。

例 25 As we know. 众所周知。

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

(7)当定语从句的关系代词指的是先行词本身时，只能用which。

例 27 These apple trees, which I planted tree years ago, have not borne any fruit.这些苹果树是我三年前种下的，没结出任何果实。

例 28 The Thames, which is now clean enough to swim in, was polluted for over a hundred years.泰晤士河，现在已经很干净，可以在里面游泳，它曾被污染了一百多年。

(8)带介词的典型的定语从句，必须用which，不能用as。

例 29 There is a great deal of oxygen around us, without which we could not live. 我们周围有许多氧气，没有它我们就无法生存。

例 30 The shed in our garden, in which we often played, has lasted for a long time. 我们经常玩耍的花园里的那个棚子，已经有很长时间了。

(9)as常与从句中的know，see， hear，expect等动词连用，也常用于as often happens，as is often the case(常有的事)等句子中;而which一般不用于以上情况。

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

(10)当后置的非限制性定语从句是否定结构时，只能用which引导。

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

2. 引导限制性定语从句时which与as的区别：

(1)先行词如果是表示物的名词或代词，在从句中又做介词的宾语时，只能用which。

例 33 This is the pan in which I boiled the milk. 这就是我煮牛奶的锅。

(2)前面有as时,引导定语从句的关系代词用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时，引导的定语从句的关系代词用as, 不用which。

例 35 Such women as know Tom thought he was charming. 认识汤姆的女人都认为他很迷人。

例 36 I have never heard such stories as he tells. 他讲的那些故事我从没听过。

(4)前面有the same时，引导定语从句的关系代词用as而不用which。

例 37 We are facing the same problems as we did years ago.我们正面临着和多年以前同样的困难。

例 38 This is the same wallet as I lost. 这只钱包与我丢失的那只相同。

(5)单个词引导限制性定语从句时，一般不用as而用which和that。由于关系词在从句中作宾语，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)“介词+关系代词”引导定语从句时，只能用which。

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

注：此时的which不能用as来代替。另外还应注意：引导定语从句时，which不能单独作定语，此时不管先行词是人还是物，都只能用whose引导，但指物时，可以用of which替换。