四六级考试常考重点英语语法汇总

1、四六级考试常考英语语法一.定语从句引导定语从句的有关系代词as, who, whom, whom, which, that和关系副词 when, where, why 等。1 .as引导定语从句（1） as引导定语从句,相当于which。如 I am from shanghai, as/which you know。但as引导的定语从句可以放在句首，而which不能；例： As you know, I am from shanghaio）（2） as可作为关系代词来引导定语从句，既可以单独引导从句，乂可以与主 句中的the same或such相呼应，从句中的谓语动词常省略。2 .关系代词tha

2、t与which用法区别：（1）which可以引导一个非限制性定语从句，that则不能；（2） which之前可以有介词，that之前则不能；（3）只能用that,而不能用which的主要情形:当先行词是 all, anything, few, little, much, none, nothing, something 等不定代词时；一一当先行词被序数词或形容词最高级修饰时；当先行词被the very, the only等词修饰时。例： Medical researchers are painfully aware that there are many problems to which t

3、hey have not found solutions so far。二.状语从句1.让步状语从句(1) 由 no matter + wh-疑问词no matter what 和 wh-疑问词>ever whatever o但wh-疑问词+ever【whatever】引导的名词从句则不能用no matter 替换。Take the coat , no matter what coat it is / whatever coat it is .(2) No matter whether.or结构中可将 no matter 省略，形成 whetheror或 whether.or not引导

4、选择条件句。彳列；The substance does not dissolve in water whether it isjheated or note2.条件状语从句>翻译条件状语从句时，要注意时态的选择。例；Please come here at ten tomorrow morning if it is convenient for you。条件状 语从句，用if引导；主句是祈使句，相当于将来时态，故从句应用一般现在 时。3 .时间状语从句彳列； We do not know it until a doctor discovered it by chance o4 .原因状语从

5、句常见引导原因状语从句的引导词有；because, as, now that/since, in that 等。三.名词性从句1 .主语从句汉语中的“的字结构可译成英语的主语从句，用what引导，相当于the thing thato仞J： What many people have not realized is that read books is a insteresting thingo2 .表语从句In my seventies, one change I notice is that I am more easily to get tired than before o四.比较结构1

6、. as.as【与.一样】，morethan【比更】，a bit/a little/a lot/even/far/gretly/many/much/sightly/still+形容词/副词比较级这些结构。主意： more than 表示'不只是， 只不过；no more.than.=not.any more than., 表示，与一样不.I彳列：I would prefer shopping online to shopping in a department store because it is more convenient and time-savingoASince my c

7、hildhood I have found that nothing is more attractive to me than readingo2. The more.the more.，越.越"例：The more you explain , the more confused me 03倍数表达法A is倍数+the size/length/width of B【A是B的几倍大/长/宽】A is倍数+形容词或副词原级+asB【A是B的几倍】A is倍数more than B【A是B的几倍】例： On averaget it is said,visitors spend only

8、 half as much money in a day in Leeds as in London.4,表示与相 比较的短语compare with和in comparison with彳列：Your losses in trade this year are nothing compared with/in comparison with mineo五.情态动词1 .情态动词中的must, can, could, may, might都表示推测。其中must可能性 最大，can和could其次，may和might最小。2 .情态动词完成时所表达的意义:could have done本科可能

9、做may/might have done 也许做 ishould have done 本应做must have done 肯定做过六.倒装结构1 .有否定含义的副词或短语位于句首作状语，这类词有：neither, never, no, rarely, hardly.when, little, few, in no case , no sooner.than 等。例：Not until he fanish his work did he realize he was seriously illo2 .含有only的状语或宾语位于句首时，其句子的主谓要部分倒装。例： Not only did he

10、 charge me too much, but he completed his missiono3.虚拟语气的让步状语从句中，在省略了 If的情况下主谓部分倒装。Had I taken your advice if I had taken your advice , all this misery might have been avoided o七.虚拟语气1 .虚拟语气用于非真实条件句(1)由if引导的非真实条件句表示对现在过去将来的事实进行假设时.，主 从，句的谓语动词形式如下所示表虚拟的时间If从句谓语形式主句谓语形式现在过去时Would/should/could/might+ 动

11、词 原形过去Had+过去分词Would/should/could/might+have done将来一般过去时Were to+动词原形Would/should/could/might+ 动词 原形Should+动词原形例：If she had returned an hour latter, Mary would not have been caught in the heave rain。（2）有些介词或介词短语含有隐含的条件含义，其虚拟形式与if引导的非真 实条件状语从句类似，需根据从句所用的时态，来选择主句谓语形式。这些词 包括：without, but for, were it not

12、 for 等。2 .虚拟语气用于状语（1） lest, in case或for fear that引导的目的状语从句中，谓语动词用 【should+动词原形】）（2）在as if或as though引导的方式状语从句中，谓语动词虚拟式的变化要依 据对过去，现在，将来的假设选择适当的动词虚拟式。列：You would better take a sweater with you in case it gets cold °3 .虚拟语气用于宾语从句中（1）Wish后的宾语从句可用三种谓语动词形式表示虚拟：一般过去时表示对现在情况的假设过去完成时表示对过去情况的假设would+动词原形表

13、示对将来的愿望例：sometimes I wish I were living in a different time and different placeo（2） would rather, would sooner, might as well, would prefer 后面跟虚 拟语气表示愿望，意为宁愿，但愿，形式为：would ranther/sooner+主语+谓语动词过去式表示现在或将来的愿望would ranther/sooner+主语+动词过去完成时表示过去的愿望例：I would rather I had not gone to the party yesterday o（3） if only引导的感叹句表示但愿，要是.就好了。其用法和wish基 本相同，只是感情色彩更强烈。（4） 在表示命令，建议等动词后的宾语从句中要求用虚拟语气形式，谓 语形式为should+动词原形例：The teacher raquired that we should hand in our homework by Wednesday o4.it is +形容词/名词+th