2018英语专四语言知识题必备知识点：主语从句的引导词

2017-10-17 17:37:12来源：网络

2018英语专四语言知识题必备知识点：主语从句的引导词

　　英语的从句包括主语从句、表语从句、状语从句、定语从句、同位语从句、宾语从句等。根据从句部分在句子里不同的表情达意作用，又可细分为更多类型，如状语从句包含表示原因的原因状语从句、表示时间概念的时间状语从句、表示假设的条件状语从句;根据从句语义的重要性和语气的强弱又可进一步细分，比如定语从句可细分为限定性定语从句(此时从句含义与主句紧密相关)以及非限定性定语从句(此时从句含义与主句联系不紧密，仅起到补充说明作用)。综上所述，各种从句都有各自常用的引导词，如限定性定语从句常用that引导，非限定性定语从句常用which引导，条件状语从句常用if引导，主语从句常用what引导等。考生应该根据上述从句分类，搞清常用的引导词的用法。

　　引导主语从句连词有that,whether,who,what,whatever等

　　定义:如果一个句子在复合句中充当一个主语,那么这个句子就是主语从句. 第一部分：常规主语从句，即句子在复合句中充当一个主语 (1)That he finished writing the composition in such a short time surprised me. (2)Whether we will go for an outing tomorrow remains unknown. (3)Who will be our monitor has't been decided yet.

　　(4) Whom we must study for is a question of great importance. (5)What caused the accident remains unknown. (6)Whatever you did is right.

　　(7)Whose watch was lost is unknown. (8)What we need is time.

　　(9)What we need are good doctors. 小结:

　　(1)引导主语从句连词有that,whether,who,what,whatever等 (2)连词位于句首不能省略

　　(3)主语从句大多数情况下视为单三,但也有例外,如例9

　　第二部分：为了防止句子头重脚轻，通常把形式主语it放在主语位置，真正主语搁置于句末

　　(1)It is certain that he will win the match.

　　(2)It is true that he has made a very important discovery in chemistry. (3)It is very likely that they will hold a meeting. (4)It is strange that he should do that.

　　(5)It is important that we all should attend the meeting.

　　(6)It is strange that the man should have stuck to his silly ideas.

　　(7)It is a pity that we won't be able to go to the south to spend our vacation. (8)It is still a mystery what caused the accident.

　　(9)It is said that he has gone to Taiwan.(=He is said to have gone to Taiwan) (10)It is known to all that the gun powder was first invented by the Chinese. (11)It is suggested that the work should be done with great care.

　　(12)It seems that he has seen the film.(=He seems to have seen the film) (13)It happened that the two cheats were there. (=The two cheats happened to be there) 小结:

　　(1)以that 引出的主语从句,常以形式主语it引导. It is +形容词/名词/某些动词ed + that 从句.

　　(2) 在有些that从句中要用虚拟语气 (should+do/should+have done)例句4,5,6,11.

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