语法是英语学习的基础，也是英语六级考试的基础，掌握好英语语法无论是对六级考试还是以后的英语学习都是有很大帮助的。下面新东方网英语六级频道为大家整理了英语六级语法常考知识讲解，希望能为大家带来帮助!

　　2017年12月英语六级语法常考知识讲解汇总

　　定语从句

　　限制和非限制性定语从句: 限制性定语从句是名词词组不可缺少的一个组成部分, 去掉了会造成病句或意义不明确; 非限制性定语从句属于补充说明性质, 去掉了不会影响主要意义, 通常用逗号与它的先行词分开.

　　The boys who wanted to play football were disappointed when it rained.

　　The boys, who wanted to play football, were disappointed when it rained.

　　如果定语从句的先行词是专有名词, 或是带有形容词性物主代词(my, his, etc)或形容词性指示代词(this, that, etc)作限定词, 其后的定语从句通常都是非限制性的:

　　Mary Smith, who is in the corner, wants to meet you.

　　Her mother, who had long suffered form arthritis, died last night.

　　All these books, which have been donated by visiting professors, are to be used by the postgraduates.

　　在非限制性定语从句中只能用who/whom指人, 用which指物,通常不用that替代.

　　My father, who had been on a visit to America, returned yesterday.

　　All the books, which had pictures in them, were sent to the little girl.

　　定语从句的引导词

　　that, who, whom: 非限制性定语从句, 如果修饰人, 一般用who, 有时用that (作主语时用who较多). 如果关系代词在从句中作宾语, 就应当用宾格 whom 或that, 但在大多数情况下都可以省略掉, 在口语中可用who代替whom.

　　Here is the man (whom) you’ve been looking for.

　　He is a man (that) you can safely depend on.

　　The people (who/that) you were talking to were Swedes.

　　There are some people here who I want you to meet.

　　但在介词后只能用whom:

　　This is the man to whom I referred.

　　但在口语中一般都把介词放到句子后面去, 这时可用that, 但省略时更多一些.

　　Have you met the person about whom he was speaking?

　　Have you met the person (that) he was speaking about

　　The girl to whom I spoke is my cousin.

　　The girl (who/that) I spoke to is my cousin.

　　限制性定语从句如果修饰“物”, 用关系代词that的时候较多, 也有时用which.. 当这个代词在从句中是用作宾语时, 在绝大多数情况下都是省略的, 特别是口语中(尤其是当被修饰的词是all, everything等词时):

　　Have you everything you need?

　　(Is there) anything I can do for you?

　　All you have to do is to press the button.

　　在介词后只能用which, 在口语中一般都把介词放到从句后部去, 这时可以用that, 但省略的时候更多一些:

　　The tool with which he is working is called a wrench.

　　The tool (that) he is working with is called a wrench.

　　This is the question about which we’ve had so much discussion.

　　This is the question (that) we’ve had so much discussion about.

　　定语从句一般是修饰名词或代词的, 但间或也可以修饰整个句子a), 或是句子的一部分 b), 引导词用which:

　　They have invited me to visit their country, which is very kind of them.

　　The activity was postponed, which was exactly what we wanted

　　When deeply absorbed in work, which he often was, he would forget all about eating and sleeping.

　　She was very patient towards the children, which her husband seldom was.

　　whose: 在表示“...的”这个概念时, 可用所有格 whose; whose 用于指物, 有时可与of which交替使用, 通常的词序是名词词组 + of which:

　　Is there anyone in your class whose family is in the northeast?

　　We had a meeting whose purpose was completely unclear. (…the purpose of which was…)

　　He’s written a book the name of which I’ve completely forgotten. (…whose name I’ve…)

　　of which前的名词词组也可以由some, any, none, all, both, several, enough, many, most, few以及基数词担任; 这些词也能用在 of whom之前.

　　The buses, most of which were already full, were surrounded by an angry crowd.

　　It’s a family of eight children, all of whom are studying music.

　　关系副词 when, where, why: 它们的含义相当于 at which, in which, for which, 因此它们之间有交替使用的可能.

　　The day when he was born…

　　on which he was born…

　　which he was born on…

　　The office where he works…

　　at which he works…

　　which he works at…

　　有时可用that替代关系副词, 在口语中that 可省略.

　　Every time (that) the telephone rings, he gets nervous.

　　This was the first time I had serious trouble with my boss.

　　Do you know anywhere (that) I can get a drink?

　　This is the place (where) we met yesterday.

　　That is the reason (why) he did it.

　　在the way 后也可用that 替代in which, 在口语中that也可省略.

　　This is the way (that/in which) he did it.

　　That’s the way I look at it.

　　如果定语从句中谓语为 there is, 作主语的关系代词也常可省掉:

　　I must make full use of the time there is left to me and do as much as I can for the people.

　　This is the fastest train (that) there is to Nanjing.

　　定语从句的简化: 定语从句与不定式结构, -ing分词结构, -ed分词结构以及无动词分句等有着转换关系.

　　He was the only one to realize the danger (= who realized the danger).

　　The woman driving the car (= who was driving the car) indicated that she was going to turn left.

　　The man injured by the bullet (= who was injured by the bullet) was taken to hospital.

　　All the women present (= who were present) looked up in alarm

　　2017年12月英语六级语法常考知识讲解汇总