学法新探
在非限制性定语从句中,which 与as 两者既有相通之处,又有相异之点。如果把握不到位,区别不恰当,极易出错。对此,笔者就非限制性定语从句中which 与as 的用法差异进行了剖析,以期同学们能够准确辨析和运用。
辨析之一:观“位置”
在非限制性定语从句中,which 与as 的位置有所不同。一般地,which 引导的非限制性定语从句不能置于句首,多位于主句之后;而as 引导的非限制性定语从句的位置则十分灵活,不仅可以置于主句之中和主句之后,而且可以置于句首,即置于主句之前。
比如,①Jake passed the driving test ,which sur-prised everybody in the office.杰克通过了驾驶考试,这使办公室里的每个人都感到惊讶。(which 引导的非限制性定语从句置于主句之后)
②Paper ,as we know ,was first made in China.众所周知,纸是中国人发明的。(as 引导的非限制性定语从句置于主句之中)
③She comes from South ,as I know from his ac-cent.我从他的口音中知道她来自南方。(as 引导的非限制性定语从句置于主句之后)
④As is known to all ,China has developed quickly these years and it has become one of the most important countries in the world.众所周知,近年来,中国的发展十分迅猛,目前已成为世界上最重要的国家之一.(as 引导的非限制性定语从句置于句首)
从上述几个例子可以看出,which 与as 引导的非限制性定语从句都可以置于主句之后,两者有时可以互换。但需要注意的是,当在主句之后的非限制性定语从句为否定句或带有否定意味时,只能用which 引导,不能用as 。如:①The weather turned out to be very good ,which was more than we could expect.结果天气非常好,这一点我们没有料到。(非限制性定语从句带有否定意味,只能用which )②That Tom will marry Jenny ,which has not been announced yet ,has spread around .汤姆要娶珍妮这件事还没宣布,却已被传得沸沸扬扬。(非限制性定语从句为否定句,只能用which )
辨析之二:识“语义”
在非限制性定语从句中,关系代词which 和as 在句中的语义是存在差异的。which 通常可以意为“这,那,这(那)件事,这(那)一点”,相当于and this 、and that 。如:①My teacher said I passed the
exam ,which made me very happy.=My teacher said I passed the ex-am ,and this made me very happy.我的老师说我通过了考试,这使我非常开心。②The elephant ’s ears are
like fans ,which anybody can see.大象的耳朵像扇子,
这一点任何人都能看出来。
as 意为“正如,像”,常用句式有:as has been said be-fore (如前所说),as is mentioned above (如上所述),as is well known (众所周知),as I understand it (据我所知),as is reported in the newspaper (正如报纸上报道的那样),as we had expected (正如我们所预料的那样),as (it )often happens (像往常一样),as (it )seems likely (似乎有可能),as is natural 等。
如:①Power is equal to work divided by the time ,as is well known.众所周知,功率等于总功除以时间。②She has won the first prize ,as it often happens.像往常一样,她得了第一名。③As has been said before ,read-ing is a good way in learning English.正如前面所说,朗读是学英语的一种好方法。④As is mentioned above ,the number of the students in senior high school is increasing.如上所述,高中生的人数正在增加。
辨析之三:明“句法”
在非限制性定语从句中,which 和as 的句法差异主要体现在如下方面:
(1)在非限制性定语从句中,倘若关系代词指的是先行词本身,只能用which ,而不能用as 。如:①These peach trees ,which I planted two years ago ,have not borne any fruit.这些桃树是我两年前种下的,没结出任何果实。②The Science Museum ,which we visit-ed during a recent trip to Britain ,is one of London ’s tourist attractions.我们最近去英国时参观过的科学博物馆,是伦敦的旅游景点之一。
(2)在带有介词的非限制性定语从句中,关系代词只能用which 引导,不能用as 。如:Mark was a stu-dent at this university from 1998to 2002,during which time he studied very hard and was made president of the Student Union.马克从1998年到2002年是这所大学的一名学生,期间他学习非常刻苦,并被任命为学生会主席。
限制性从句(3)在非限制性定语从句中,which 后的be 动词不可省略,而as 后的be 动词则可以。如:①The device is set up to examine a lens ,as (is )shown in the figure.如图所示,这种仪器是为检验透镜而安装的。(此处is 可以省略)②He said he saw me in the cinema ,which was a lie.他说他在那里看见我,事实上这是一个谎言。(此处was 不可省略)
总之,在平时的英语学习中,同学们要做到善于归纳,明辨细微差异,查漏补缺,这样自然就能运用自
如。
(作者单位:江苏省滨海中学)
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