1、 语法专题二：名词性从句1. 名词性从句的基本概念：1) 主语从句：在句中充当主语；亦可用it作形式主语，主语从句置于句末。2) 宾语从句：在句中充当及物动词或介词的宾语；亦可用it作形式宾语，宾语从句置于句末。3) 表语从句：在句中充当系动词的表语。4) 同位语从句：常置于fact, idea, news, promise, doubt, suggestion, possibility, belief等表示有内容的名词后，起解释、说明作用。2. 注意：1) 名词性从句要用陈述句语序。2) 名词性从句中缺少主语、表语、宾语时：常用what 导，亦可用which表示选择，用who/whom/wh
2、oever指人。 缺少状语：用where（表地点）, when（表时间）, how（表方式）, why（表原因）。3) 如不缺成份：主语从句、同位语从句用that引导，不能省略； 表从、单个动词宾从可省略引导词that； 介词宾从、第二个宾从，引导词that一般不省略； it作形式主语或宾语时，引导实际主从或宾从，一般that不省略； 当主从、宾从本身为复合句时，引导词that不省略。 如：He told us sadly that what he had done secretly was discovered by his parents.4) 含宾从的复合句中，主句和从句的时态保持一致，
3、但如果从句中表示是客观现象，虽然主句是过去时态，从句仍用一般现在时。5) 主语从句做主语，谓语动词用单数；如果由and 连接两个或两个以上的主语从句做主语时，谓语动词用复数；由两个或多个连接词引导一个主语从句，谓语动词用单数。6) 当主句是I/We think（或suppose, expect, believe, imagine, guess）时，其后的宾语从句如果是否定的，常常把否定词not从从句中移到主句中。7) 只能用whether，不能用if表示“是否”的情况如下：(1) 在表语从句和同位语从句中；(2) 在主语从句中，如果用it做形式主语，whether和if都能引导主语从句，否则，
4、只能用whether (3) 在介词之后； (4) 后面直接跟动词不定式； (5) 与or not连用； (6) 引导让步状语从句，只能用whether。8) 同位语从句与定语从句的区别：同位语从句常放在表示具体含义的名词后，解释名词的含义或内容，该名词在从句中不充当成份；定语从句是对先行词限定和修饰，先行词在定语从句中充当成分。巩固练习：1. We should think carefully about _ Mr. Needham said at the meeting. A. that B. what C. which D. /2. _ you have seen things like
5、 these before doesnt matter. A. If B. Whether C. What D. When3. She took it for granted _ Id be back home an hour ago. A. that B. whether C. if D. when 4. At that time I had no idea _ I could hand it to him without being seen. A. if B. how C. which D. that how5. Last Sunday he promised _ today, but
6、he hasnt appeared yet. A. that he would come B. that he will comeC. he will come to see me D. whether he would come6. What a pity _ is _ you didnt arrive by daylight. A. there; because B. it; that C. he; when D. that; for7. Father made a promise _ I passed the examination he would buy me a new dicti
7、onary. A. that B. if C. whether D. that if 8. _ is the most useful invention? A. Do you think which of these B. Which of these do you thinkC. Which of these you think D. You think which of these9. -I believe _ youve done your best and _ things will improve. -Thank you. A. that; / B. /; / C. what; th
8、at D. /; that10. It depends on _ we have enough time. A. if B. if or not C. that D. whether 11. You will realize _ breaks the law will be punished. A. that those who B. that those that C. whoever D. those whoever12. I dont doubt _ he will come. A. that B. if C. what D. whether13. When and why he cam
9、e here _ yet. A. is not known B. are not known C. has not known D. have not been known14. The city is no longer _. A. what it is B. that it used to be C. which it was D. what it used to be 15. _ was the idea _ the wife thought of ? A. What; that B. That; what C. How; why D. Why; how 16. One of the m
10、en held the view _ the book said was right. A. what that B. that what C. that which D. which that17. _ you dont like him is none of my business. A. What B. Who C. That D. Whether18. _ he really means is _ he disagrees with us. A. What; that B. That; what C. Why; that D. If; what19. - Dont you believ
11、e me?-_. Ill believe _ you say. A. No; whatever B. Yes; no matter what C. Yes; whatever D. No; no matter what20. Lei Feng was always thinking of _ he could help others. A. that B. how C. when D. which21. Can you tell me _? A. who is that woman B. who the woman is C. whom is the woman D. that woman is22. Output is now six times _ it was before liberation. A. that B. which C. what D. those23. After months of research there was little hope _ the lost car might be found. A. that B. which C. when D. how名词性从句：BBABABDBDDCAADABCACBBCA
