1 which引导定语从句的用法。which可以最广泛地引导一个定语从句,来修饰一个名词或者名词性结构。which和that的最主要区别是,which可以引导非限制性定语从句。比如:I have an apple, which is red. 简单来说,修饰的名词和which之间有个逗号了,这里就只能用which。再比如:The answer that/which is provided by Wong is wrong. 这里that和which可以互换。这是基础的东西,再讲5点。(例子都是瞎想的,未经推敲,大概明白我的意思就好。)
第一点,表示人的时候可以用who,当然有时候也需要用whom,不过标准书面语现在whom用的很少,直接用who就可以了。表示时间可以用the time when,表示地点可以用the place where。不过which还是比较百搭的。
第二点,which前可以加介词。比如,I have a house in which my aunt lives. which引导非限制性定语从句,前面也可以加介词。
第三点,which引导的定语从句,大家可能看出来比较啰嗦。比如The answer which is provided by Wong is wrong.这里不如直接用The answer provided by Wong is wrong.所以,出于简洁,which引导的从句可以用动词+ing或者动词+ed开头的短语来代替。
第四点,which不能,注意是不能引导一个定语从句,修饰前面整个句子。而-ing形式引导的结构做伴随状语(伴随动作或者伴随结果)可以修饰整个句子。比如:She married a rich man, which left her boyfriend in that small town. 这里的which在语法上只能修饰man,而不能修饰整个句子。这里应该这样表达:She married a rich man, leaving her boyfriend in that small town.
第五点,which可以根据后面的动词,修饰远一点的名词。比如:I eat all the apples of the office, which taste well. 这里,taste是复数形式,因为在修饰apples而不是最靠近的office。
3 被动语态
简单来说,能不用就不用。被动语态肯定是wordy的,比如I eat an apple. An apple is eaten by me. 哪个简单明了,一看就知道。尤其是句子中各种短语从句套来套去,被动语态看起来就更难受了。有些时候不得不用被动语态,比如:The valley was discovered 30 years ago.这里没有必要去强调谁在discover,所以可以用被动语态。
4 and及平行结构
and前后要平行,比如writing an article and performace of arts are similar. writing和performance不能平行。I could count to ten and the earth is big. 这里也不平行,不能用and。And用在一个句子开头,99%是错的,不要用。
5 比较级
只能用than表示比较,比较级只有完全一致的内容可以省略,不一致的必须补足。没有than,直接用比较级多半是错的。
6 因果关系的表达
用because,since。如果原因只有一个名词(名词性结构),用because of 也可以,due to也可以。for可以表示轻微的因果。随便举几个例子:
She is not in that room, because the room is empty.
She is not in that room, since I just checked the room.
She is not in that room, for I saw her in another place.
The price of soybean is lower and lower because of competition.
The price of soybean is lower now due to competition among suppliers.
7 代词的指代
一个句子中的一个代词,比如they,只能指代同一个东西。代词指代离代词最近的,合理的那个词。都跨越好几个句子了就不要用代词指代了。this that these those能不用就不用。
8 动名词
动名词不是名词,不可以和名词并列。很多动词都有名词形式,尽量少用动名词,用的话要么错,要么暴露词汇量捉急。动名词不要做句子的主语。