2019英语专八必备语法复习：动词的不定式

2019英语专八必备语法复习：动词的不定式

　　语法是英语专八的基础，语法知识贯穿在整个英语专八考卷的各个题型中。

　　英语专八语言知识题会直接考查语法知识;阅读理解题和汉译英中有大量的长难句，这些句子只有具备一定的语法知识才能正确分析;专八作文中要写出正确无误的句子，也需要语法知识。这部分基础如果欠缺，其它的综合能力提高起来将会很慢，所以所有考生都务必重视英语专八语法的复习。

2019英语专八必备语法复习汇总

　　动词不定式及其短语还可以有自己的宾语、状语，虽然动词不定式在语法上没有表面上的直接主语，但它表达的意义是动作，这一动作一定由使动者发出。这一使动者我们称之为 逻辑主语，其形式如下：

　　(1)语态

　　如果动词不定式的逻辑主语是这个不定式所表示的动作的承受者，不定式一般要用被动语态形式。如：

　　It's a great honour to be invited to Mary's birthday party.(不定式作主语是被动语态to be invited是被邀请)

　　It was impossible for lost time to be made up.(不定式作主语)

　　I wish to be sent to work in the country.(不定式作宾语)

　　Can you tell me which is the car to be repaired?(不定式作定语)

　　He went to the hospital to be examined.(不定式作状语)

　　在There be结构中，修饰主语的不定式可用被动，也可用主动。如：There are still many things to take care of (to be taken care of).但有时两种形式表达的意思不同，如：There is nothing to do now.( We have nothing to do now.) There is nothing to be done now.(We can do nothing now.)

　　(2)时态

　　1) 现在时：一般现在时表示的动词，有时与谓语动词表示的动作同时发生，有时发生在谓语动词的动作之后。

　　He seems to know this.

　　I hope to see you again. = I hope that I'll see you again.　我希望再见到你。

　　2) 完成时：表示的动作发生在谓语动词表示的动作之前。

　　I'm sorry to have given you so much trouble.

　　He seems to have caught a cold.

　　3) 进行时：表示动作正在进行，与谓语动词表示的动作同时发生。

　　He seems to be eating something.

　　4) 完成进行时：

　　She is known to have been wreaking on the problem for many years.

　　一般在情绪后加to do to do 也表将来

　　疑问词+不定式结构疑问词who,what,which,when,where,whether,how后可接不定式构成不定式短语，在句中作主语、宾语、表 语等。如：

　　①When to leave for London has not been decided yet. (不定式在句子中做主语)

　　②Mr. Smith didn't know whether to leave or stay there. (不定式在句子中做宾语)

　　③I asked Professor Xu how to learn English well. (不定式在句子中做直接宾语)

　　④The question was where to get the medicine needed. (不定式在句子中表语)

　　以上例句中疑问词+不定式部分，均可转换为相应的从句形式。如：①When we shall leave…③…how Icould learn…

　　经常在这种结构中使用的动词有：consider,decide,discover,explain,find out,forget,hear,know,lea rn,observe,understand,wonder等。

　　语法功能

一、作主语

　　动词不定式作主语时，句子的谓语动词常用单数，其位置有以下两种：

　　(1)把不定式置于句首。如：

　　To get there by bike will take us half an hour.

　　(2)用it作形式主语，把真正的主语不定式置于句后，常用于下列句式中。如：

　　①It+be+名词+to do

　　It's our duty to take good care of the old.

　　②It takes sb+some time+to do

　　How long did it take you to finish the work?

　　③It+be+形容词+for sb+to do

　　It is difficult for us to finish writing the composition in a quarter of an h

　　It is stupid of you to write down everything (that) the teacher says.

　　④It seems(appears)+形容词+to do

　　It seemed impossible to save money.

　　在句型③中，常用表示客观情况的形容词，如：difficult,easy,hard,important,impossible,necessary 等;在句型④中，常用careless,clever,good,foolish,honest,kind,lazy,nice,right,silly,stupid,wise等 表示赞扬或批评的词。在不定式前的sb，可看作其逻辑主语。这一句式有时相当于Sb is+形容词+to do句式 ，如：It's kind of you to help me with my English.=You are kind to helpme with my English.

　　(3)举例

　　(1) It's easy (for me) to do that.我做这事太容易了

　　easy,　difficult,　hard,　important,　possible,　impossible,　comfortable,　necessary,　better;

　　the first,　the next,　the last,　the best,　too much,　too little,　not enough

　　It's so nice to hear your voice.

　　听到你的声音真高兴。

　　It's necessary for you to lock the car when you do not use it.

　　当你不用车的时候，锁车是有必要的。

　　(2) It's very kind of him to help us.　他帮助我们，他真好。

　　Kind,　nice,　stupid,　rude,　clever,　foolish,　thoughtful,　thoughtless,　brave,　considerate(考虑周到的),　silly,　selfish(自私的)

　　例句:

　　It was silly of us to believe him.　我们真愚蠢，竟然相信了他。

　　It seemed selfish of him not to give them anything.　他不给他们任何东西，这显得太自私了。

　　注意：(1) 其他系动词如，look，appear等也可用于此句型

　　(2) 不定式作为句子成分时，动词用单数形式。

　　(3) 当不定式作主语的句子中又有一个不定式作表语时，不能用It is… to…的句型

　　(对)To see is to believe.　眼见为实。

　　(错)It is to believe to see.

专四专八精选好课 暖心助学

新东方好老师 手把手带学