高考英语二轮复习考点练习考点21主语从句、表语从句和同位语从句 (含解析)

考点20 主语、表语和同位语从句 高考频度：★★★★★ 考向二 主语从句 1.主语从句在复合句中充当主语，大多数主语从句都可以用it作形式主语而把主语从句置于句尾。 2.that引导主语从句时可用it作形式主语，that不可省；what引导的主语从句表示＂……的东西＂时，一般不用it作形式主语；whatever，whoever，whichever一般也不用it作形式主语。 ☞That she will succeed is certain. 常见的it替代that引导的主语从句的句式主要有以下几种： (1)It＋系动词＋形容词(necessary，right，likely，unlikely，wrong，important，certain，clear，obvious，strange，normal等)＋that从句 ☞It is certain that most of the farmers have brought in more money by all means. (2)It＋be＋名词(短语)(a pity，a shame，good news，a fact，an honour，a wonder，no wonder等)＋that从句 It’s no wonder that you’ve achieved so much success. (3)It＋be＋过去分词(said，told，heard，reported，decided，suggested，advised，ordered，remembered，thought，considered，well­known，announced等)＋that从句 ☞It is said that the professor has already succeeded in carrying out the experiment. (4)It＋特殊动词(seem，appear，happen，matter)＋that从句 ☞It happened to me that I had been away when he called. ☞It is certain that she will succeed. 注意：(1)在＂It is necessary/important/strange/natural...＋that从句＂结构中，从句谓语常用＂(should＋)动词原形＂形式。 【拓展延伸】主语从句的引导词 引导词 作用 引导词 作用 that 无词义，在从句中不充当成分，但不能省略 how 多么，怎样，作方式状语或程度状语 who 谁，作主语、宾语 when 何时，作时间状语 whom 谁，作宾语 where 在哪儿，作地点状语 what 什么，可作主语、宾语、表语、定语 why 为什么，作原因状语 which 哪一个，哪些，作主语、宾语、定语 whether 是否 【特别注意】当作主语的句子太长时，为保持句子平衡，常用it作形式主语，而将真正的主语置后。if＂是否＂，不可直接引导主语从句(用it作形式主语时可以) 。 3. 主语从句的特殊用法 （1）主语从句与定语从句的转换 ☞What is needed has been bought. ☞All that is needed has been bought. 所有需要的都被买了。 （2）几个特殊句型之间的转换 ☞It is known to all that China has joined the WTO. As is known to all, China has joined the WTO. What is known to all is that China has joined the WTO.众所周知，中国已加入WTO。 4. 从句作主语时，句子谓语动词的单复数问题 (1)从句作主语时，谓语动词一般用单数。 That they are not going to the cinema is a big surprise to us.他们不去看电影，这使我们感到很惊讶。 (2)what引导的从向作主语，谓语动词一般用单数;若从句谓语或从句后的表语是复数形式,则谓语动词常用复数。 What she said is wrong.她所说的是错误的。 What we need are books.我们所需要的是书籍。 1.(2018·天津卷·单项填空)The gold medal will be awarded ___________to wins the first place in the bicycle race. A. whomever B. wherever C. whoever D. whatever 【参考答案】C 【答案解析】考查名词性从句连接词。句意：无论谁获得自行车比赛第一名，金牌将授予他。分析句子可知，宾语从句中缺少主语，故用whoever，表示“任何人，无论谁”。故选C。 2.（2017·北京卷·单项填空） Every year, ________ makes the most beautiful kite will win a prize in the Kite Festival. A. whatever B. whoever C. whomever D. whichever 【参考答案】B　 【答案解析】考查主语从句。分析句子结构可知，________ makes the most beautiful kite作主语，且所填词指人，既作从句的主语又作主句的主语，所以选 whoever(whomever不能作主语)。句意：每年， 在风筝节上风筝做得最漂亮的人都会赢得奖品。 3.（2016·江苏卷·单项填空）It is often the case ____________ anything is possible for those who hang on to hope. A. why B. what C. as D. that 【参考答案】D 【答案解析】考查主语从句。本句中it是形式主语，真正的主语是连接词that引导的主语从句，连接词that在本句中不充当任何成分，只是一个引导词而已，不能省略。连接副词why要在句中作状语，连接代词what通常在句中作主语、宾语或表语等；as通常不引导名词性从句。句意：对于那些心存希望的人一切皆可能是事实。故D正确。 考向四表语从句 引导表语从句的连接词主要有： 连接词：that，whether 连接代词：who，whom，whose，which，what，whoever whomever，whichever，whatever 连接副词：when，where，how，why 1. 连接词引导 ☞The reason for his absence is that he hasn’t been informed. 他缺席的原因就是他没接到通知。 ☞The question remains whether they will be able to help us. 问题还是他们能否帮我们。 2. 连接代词和连接副词引导 ☞The problem is who will take charge of this shop. 问题是谁将接管这家店铺。 ☞That is when I realized the importance of journalism. 那时我才意识到新闻工作的重要性。 注意： （1）as/as if/as though引导的表语从句常跟在特定动词后面，如seem，appear，look，taste，sound，feel等。 ☞It sounds as if someone is knocking at the door. 听上去好像有人在敲门。 ☞At that time, it seemed as though I couldn’t think of the right word. 当时我似乎怎么也想不出一个恰当的字眼来。 （2）当主句的主语是reason时，表语从句一般由that引导，这种用法常见于句型The reason why... is that... ☞The reason why he came late was that he got up late. 他来得晚是因为起床晚了。 2表语从句的三个易混句式 句式 用法 例句 This/'That is why+结果 意为"这那就是.....to work there. 那就是的原因"，why 引导表语从句。 That's why I want you to work there. 我想要你在那儿工作的原因。 This/That/It is because +原因 意为"这/那是因为.....，because引导表语从句。 It's just because he |doesn't know her. 这 这仅仅是因为他不认识她 。 The reason why... is that... 意为"......的原因是……”，why定语从句，修饰先行词reason, that引导表语从句。 The reason why he didn't come was that it was raining heavily.他没有来的原因是 (当时)雨下得很大。 1.(2018·北京卷·单项填空) Without his support, we wouldn’t be _________ we are now. A. how B. when C. where D. why 【参考答案】C 【答案解析】考查名词性从句。句意：没有他的支持，我们是不会在现在这个位置的。how表方式，when表时间，where表地点，why表原因。“_________ we are now”是表语从句，结合句子的意思可知，该处指我们所处的位置，故该从句应用where引导。C选项正确。 2.（2016·北京卷·单项填空） The most pleasant thing of the rainy season is ________ one can be entirely free from dust. A. what B. that C. whether D. why 【参考答案】 B 【试题解析】 考查表语从句。句意：雨季最令人愉悦的就是人们可以完全不再受到灰尘的困扰。is后跟从句作表语，即表语从句，表语从句不缺少主语、谓语和宾语，因此用that，that只起引导作用，故选B。 考向五 同位语从句 1. 同位语从句跟在名词后面，进一步解释、说明该名词的具体内容。同位语从句常跟在名词idea, fact, news, hope, thought, suggestion等抽象名词之后； 2. 连接词that不能省略，无意义无成分； 3. 用whether而不用if引导同位语从句； 4. 连接代词who(m), which, what，whose在从句中作主语、宾语、表语或定语； 5. 连接副词where, when, why, how在从句作状语。 6.分割式同位语从句：同位语从句有时被别的词或短语把它和名词隔开：（谓语较短，同位语从句较长）。 ☞The story goes that William Tell did kill the king with tha