【英语】2019届二轮复习语法专题定语从句教案（15页word）

【英语】2019届二轮复习语法专题定语从句教案（15页word）

‎2019届二轮复习语法专题定语从句教案 Ⅰ. 概念：‎ ‎(1) 定语从句：在主从复合句中用作定语的从句叫定语从句。定语从句一般紧接在先行词(antecedent)后面。‎ ‎(2) 先行词：被定语从句修饰的成份。先行词可以为一个词，短语，或整个主句。‎ ‎(3) 引导定语从句的词叫关系词，分为关系代词和关系副词。‎ 关系词的作用：‎ ‎1) 引导定语从句，连接主句和从句，相当于一个连词；‎ ‎2) 必在从句中作某个句子成份（可以做主语，宾语，表语，定语，状语）‎ 常用的关系代词: that、 which、 who、whom、as , 在从句中作主语，宾语，whose定语)‎ 常用的关系副词（在从句中只作状语）: when、why、 where The student who answered the question was John. ‎ I know the reason why he was so angry.‎ The boy (whom) you are talking to is my brother. ‎ I'd like a room whose window looks out over the sea. 来源:学|科|网Z|X|X|K]‎ 定语从句三步：[来源:Zxxk.Com]‎ 第一找出先行词；‎ 第二看先行词在定语从句中的语法功能（做主语、宾语或状语）；‎ 第三选择合适的关系词。‎ Ⅱ. 几个关系代词的基本用法：‎ ‎●that: 可指人或物；在定语从句中作主语，宾语，表语。(指人时，相当于who或 whom；指物时，相当于which)(一般不用于非限制性定语从句; 不可置于介词后作宾语) 如：‎ ‎1. Do you know the gentleman that/who spoke just now?‎ ‎2. You can take anything ( that) you like. ‎ ‎3. What is the question (that/which) they are talking about?‎ ‎4. Here is the man ( who/whom/that ) you want to see.‎ ‎5. She's no longer the girl ( that) she used to be before.‎ ‎●which: 指物；在定语从句中作主语，宾语，表语，定语。如：‎ ‎1. The book which/that was on the desk was bought by my father.‎ ‎2. The book (which/that) I bought yesterday is very interesting.‎ ‎3. The factory in which his father works is far from here.‎ ‎[来源:学科网]‎ ‎●who, whom, whose:‎ who: 主格, 在从句中作主语，在口语或非正式用法中作宾语; 只可指人 whom: 宾格，在从句中作宾语; 只可指人 whose: 属格，在从句中作定语，可指人也可指物。‎ ‎1. I like the students who/that work hard. ‎ ‎2. All who heard the story were amazed. (代词如he, they, any, those, all, one等后多用who.)‎ ‎3. He's a man from whom we should learn. = He's a man (whom/who/that) we should learn from.‎ ‎4. A child whose parents are dead is called an orphan.‎ ‎5. I'd like a room whose window faces south. =I'd like a room of which the window faces south. ‎ ‎=I'd like a room the window of which faces south.‎ 关系代词作介词宾语： （介词+ whom / which）‎ 关系代词在定语从句中用作介词宾语时, 介词可放于从句之首, 也可放于从句之末. 但以放于句首较为正式.（介词前置，必须注意不影响动词词组的含义。） ‎ ‎1. This is the book for which you asked. =This is the book (that/which) you asked for.‎ ‎2. Do you know the person with whom I shook hands？‎ ‎= Do you know the person (whom/who/that) I shook hands with?‎ ‎3. Is this the factory to which you paid a visit last week?‎ ‎4. Is this factory the one to which you paid a visit last week?‎ ‎5. This is the girl whom they are looking after. (介词after与look构成固定词组，不可前置。look at, look for, look after, take care of等)‎ ‎●as 的用法:(as 引导定语从句, 在定语从句中作主语、宾语、表语)‎ ‎①如为限制性的，多用于the same …as ; the same as；such …as …; as many/much as；so …as等结构中。如：‎ ‎※1. I have the same book as you (have). 我有一本和你的一样的书。‎ ‎2. .---Why didn't you mention that in face of the police just now?‎ ‎--- I thought it was such a minor detail as was hardly worth mentioning. ‎ ‎3. Don't do such things as you are not sure about. ‎ 比较：I live in the same house that he used to live in.‎ ‎ I'm wearing the same shirt as you wore yesterday.‎ 比较：Here is so big a stone as no one can lift. （定语从句）‎ ‎ Here is so big a stone that no one can lift it.（结果状语从句）‎ ‎②如为非限制性的，多单独引导一个定语从句，这种定语从句可置于句首，句中或句尾，译为"正如，这一点"。（动词常为know, see, expect, point out, etc.）‎ As we all know, smoking is harmful to one's health . (as 作宾语)‎ ‎=As is known to all, smoking is harmful to one's health . （as 作主语）‎ ‎=It's known to all that smoking is harmful to one's health .‎ ‎=Smoking is harmful to one's health, as we all know .（as 作宾语）‎ ‎=Smoking, as we all know, is harmful to one' health.‎ He was a foreigner, as I knew from his accent. (宾语, 先行词是前面整个句子)‎ Ⅲ. 关系副词引导的定语从句:‎ ‎●When 指时间，在定语从句中作时间状语。其先行词是表时间的名词（如：time, day, week, tear, month, etc.）‎ He came last night when I was out.‎ We will put off the picnic until next week, when the weather would be better.‎ 注意：先行词为"时间名词"，可用when引导定语从句，when在定语从句中作状语；还可以用which或that 引导，which或that在从句中作主语或宾语。‎ 比较:1. I still remember the day when /on which my brother joined the army.（作状语）‎ ‎2. I still remember the days which/that we spent together. （作宾语） ‎ ‎3. I shall never forget the day when Shen Zhou Ⅴ was launched, which has a great effect on my life.‎ ‎●Where 指地点，在定语从句中作地点状语。其先行词是表示地点的名词，如：place, ‎ school, factory, room, etc. ‎ This is the place where I was born. ‎ I live in the room where /in which he used to live. ‎ 注意：先行词是"地点名词"，定语从句可用where引导，还可用which或that引导，which/that 在从句中作主语或宾语。 ‎ 比较: ※1. This is the factory where /in which he worked last year. （作状语）‎ ‎2. I think you have got to the point where a change is needed, or you would fail.‎ ‎3. He's got himself into a dangerous situation where he's likely to lose control of the plane.‎ ‎4. This is the park which/that they visited last year. （作宾语）‎ ‎●Why 指原因，在定语从句中作原因状语。先行词为reason 时，可用for which指代；当关系词在从句中作主语或宾语时，则用which或that 引导。如：‎ ‎1. The reason why / for which / (that) he didn't attend the meeting was that he was ill.‎ ‎2. I don't believe the reason (that/which) he gave me. （作宾语） ‎ ‎3. Have you asked him the reason that may explain his success? （作主语）‎ 当先行词为way时，the way在从句中作状语时，定语从句常用that, in which,或how引导，that常可以省略。‎ the way在从句中作主语或宾语时，则用which或that 引导。如:[来源:学科网]‎ This is the way (that) /in which I do such things.‎ 比较: Please do the experiment in the way （that/which）I have shown you.‎ Ⅳ. 限制性定语从句与非限制性定语从句的区别：‎ ‎1. 形式上，非限制性定语从句往往用逗号隔开。‎ ‎2. 语法上，非限制性定语从句一般不用that.‎ ‎3. 语义上，限制性定语从句与先行词关系紧密，起限定作用，如果去掉了这个定语从句，整个句子就不完整或者会改变意思；而非限制性定语从句与先行词关系不是很紧密，对先行词起补充说明或描述的作用。‎ This is the book I like best. 这就是我最喜欢的那本书。‎ Beijing, which has been China's capital for more than 800 years, is rich in cultural and historic relics. 北京是中国八百年之久的古都，它有着丰富的文化和历史遗产。‎ ‎4. 翻译时，限制性定语从句可译为一句（较短的一般译为"的"字结构）；而非限制性定语从句可译为两句。（见上句翻译）‎ 比较: He has a sister, who is a musician.‎ ‎ He has a sister who is a musician.‎ 引导非限制性定语从句的关系代词，指人时用who, whom, whose , 指物时用which , whose; 关系副词when，where, why, etc.‎ ‎1. He studied hard at school when he was young, which leads to his success in his later life.‎ ‎2. Tom's father, who arrived just now, is a famous scientist.‎ Ⅴ. 几个易混淆的关系代词的比较:‎ ‎●that & which:‎ 在定语从句中，which 和that 在指代事物时，一般可以互换使用，但并非在任何情况下都是这样，这里介绍宜用that, 而不宜用which 的情况.‎ ‎①先行词为不定代词,all, much, something, everything, anything, nothing, none, the one等, ‎ ‎1.We should do all that is useful to the people .‎ ‎2.There's nothing that can be said about it .‎ ‎3.Do you mean the one that was bought yesterday?‎ ‎②先行词被only, any, few, little, no, just, very, one of等词修饰时。‎ ‎1.The only thing that we could do was to wait.‎ ‎2.That's the very word that is wrongly used.‎ ‎3. The last place (that) we visited was the chemical works.‎ 比较 *This is one of the best novels that were published last year.‎ ‎ *This is the only one of the best novels that was published last year.‎ ‎③先行词是序数词时或被序数词修饰时。‎ ‎1.When we talk about Wuxi, the first that comes into mind is Tai Lake.‎ ‎2.This is the third film that has been shown in our school this term.‎ ‎④先行词是最高级或被最高级修饰时。‎ ‎1.This is the best that can be done now.‎ ‎2.The most important thing that should be done right now is how to stop him from going on.‎ ‎⑤先行词既有人又有物，用which和who都不适合，这时宜用that. 如：‎ ‎1.The writer and his novel that you have just talked about is really well known .‎ ‎2.The rider and his bike that had run over an old woman were held up by the police.‎ ‎⑥被修饰词为数词时. ‎ ‎1.Yesterday I caught two fish and put them in a basin of water .Now you can see the two that are still alive .‎ ‎⑦如果有两个从句，其中一个关系代词已用which ,另一个关系代词宜用that，以避免语言的单调或重复。‎ Edison built up a factory which produced things that had never been seen before.‎ ‎⑧疑问词是who或which，关系代词宜用that，以避免重复。‎ ‎1. Which is the book that you like best?‎ ‎2. Who is the man that is standing at the gate?‎ ‎⑨主句是There be 结构，修饰其主句的定语从句宜用that 作关系代词. 如：‎ ‎1. There is still a seat in the corner that is still free.‎ ‎⑩被修饰成分为表语时，或者关系代词本身是定语从句的表语时,该关系代词宜用that . ‎ ‎1. That's a good book that will help you a lot.‎ ‎2. My home village is no longer the place ( that ) it used to be .‎ 定语从句中宜用which而不宜用that 的情况:‎ ‎①当关系代词的前面有介词时. ‎ ‎1.A zoo is a park in which many kinds of animals are kept for exhibition.‎ ‎2.Is this the room in which Mr. White lives?‎ ‎②在非限制性定语从句中. ‎ ‎1.Crusoe's dog, which was are now very old, became ill and died .‎ ‎2.More and more people are beginning to learn English, which is becoming popular in our country. (which指代主句)‎ ‎③在一个句子中有两个定语从句，其中一个定语从句的关系代词用了that, 另一个宜用which . ‎ ‎1. Let me show you the novel that I borrowed from the library which was newly open to us. ‎ ‎④当关系代词后面带有插入语时. ‎ ‎1. Here's the English grammar which, as I have told you, will help improve your English.‎ ‎⑤先行词本身是that, 宜用which . ‎ What's that which she is looking at?‎ ‎⑥先行词是those+复数名词. ‎ A shop should keep a stock of those goods which sell best.‎ ‎(B) who & that:‎ who 和 that 指代人时，有些情况宜用who, 而不宜用that ‎ ‎①先行词为anyone, anybody, those, all, one, ones, they, he, people时. 如：‎ ‎1.The person I want to learn from is the one who studies hard and works well.‎ ‎2.Anyone who (=Whoever) failed to come to the meeting yesterday must give his reason .‎ ‎3.Those who are not fit for their work should leave office at once.‎ ‎②在There be 结构中，修饰主语的定语从句宜用关系代词who 指代人. 如：‎ ‎1.There is a gentleman who wants to see you .‎ ‎2.There are several students in our class who are still not sure about the use of attributive clauses.‎ ‎③当先行词有较长的后置定语时. 如：‎ ‎1. I met a foreigner in the park yesterday afternoon who could speak Chinese very well.‎ ‎●as & which: ‎ as & which 引导非限制性定语从句的区别：‎ ‎①位置的不同：‎ which 引导的定语从句只置于所限制的句子后；as 位置较灵活，也就是说as可置于所限制的句子前面；插在句子中或放在句子后。如：‎ ‎1. He was late again, which made his teacher very angry.‎ ‎2. Jack, as you know, is an honest man. 或Jack is an honest man , as you know. ‎ 或As you know, Jack is an honest man.‎ ‎②先行词的不同：‎ as引导非限制性定语从句时，其先行词多为一个句子；‎ which引导非限制性定语从句时，其先行词可以是一个词，一个短语或一个句子。‎ ‎1. She was very patient towards the children, which her husband seldom was.‎ ‎2. He was proud, which I dislike very much.（先行词是一个句子）‎ ‎3. He is an honest man, as is known to all. ‎ ‎③as 一般译为"正如""就像"，"这一点"‎ as we all know；as you know; as is known to all; as you see; as we can see; as has been expected; as we have imagined.‎ 用适当的关系词填空. ‎ ‎1. I will never forget the day __________ I first went to school.‎ ‎ I will never forget the day __________ we spent in Beijing.‎ ‎2. The house __________ we visited is being repaired now.‎ ‎ The house ______ Luxun once lived is being repaired now.‎ 选择适当的代词填空，注意非限制性定语从句和单句的比较。‎ ‎1.I am reading Harry Porter, _____is an interesting book.‎ ‎2.He failed in the exam._______ made his parents angry.‎ ‎3.He failed in the exam, _______made his parents angry.‎ ‎4.He has two sons. Both of ________ are teachers. [来源:Z_xx_k.Com]‎ ‎5.He has two sons, both of ________ are teachers.‎ ‎ 介词+关系代词的使用 ‎1. Do you like the book she spent $10? ‎ ‎2. Do you like the book she paid $10?‎ ‎3. Do you like the book she learned a lot? ‎ ‎4. Do you like the book she often talks? ‎ ‎5. He dug a hole he could got water from the lake.‎ 请分析一下定语从句：( 请划出定语从句，并标出先行词) ‎ ‎1. Another thing that I found very difficult was English grammar.  ‎ ‎3. You couldn’t understand people who talked fast.  ‎ ‎4. I have some ideas that may help you.  ‎ ‎5. They said something you didn’t like.  ‎ ‎6 .My friends and I talked about the rules that we have in school.‎ 定语从句专项练习题 ‎1.The place _______interested me most was the Children's Palace. A. Which B. where C. what D. in which 2.Do you know the man _______? A. whom I spoke B. to who spoke C. I spoke to D. that I spoke 3.This is the hotel _______last month. A. which they stayed B. at that they stayed C. where they stayed at D. where they stayed 4.Do you know the year ______the Chinese Communist Party was founded? A. which B. that C. when D. on which 5.That is the day ______I'll never forget. A. which B. on which C. in which D. when 6.The factory ______we'll visit next week is not far from here. A. where B. to which C. which D. in which 7.Great changes have taken place since then in the factory _______we are working. A. where B. that C. which D. there 8.This is one of the best films _______. A. that have been shown this year B. that have shown C. that has been shown this year D. that you talked 9.Can you lend me the book ______the other day? A. about which you talked B. which you talked C. about that you talked D. that you talked 10.The pen ______he is writing is mine. A. with which B. in which C. on which D. by which 11.They arrived at a farmhouse, in front of ______sat a small boy. A. whom B. who C. which D. that 12.The engineer ______my father works is about 50 years old. A. to whom B. on whom C. with which D. with whom 13.It there anyone in your class ______family is in the country? A. who B. who's C. which D. whose 14.I'm interested in ______you have said. A. all that B. all what C. that D. which 15.I want to use the same dictionary ______was used yesterday. A. which B. who C. what D. as 16.He isn't such a man ______he used to be. A. who B. whom C. that D. as 17.He is good at English, ______we all know. A. that B. as C. whom D. what 18.Li Ming, ______to the concert enjoyed it very much. A. I went with B. with whom I went C. with who I went D.I went with him ‎ ‎19.I don't like ______ as you read. A. the novels B. the such novels C. such novels D. same novels 20.He talked a lot about things and persons ________they remembered in the school. A. which B. that C. whom D. what 21.The letter is from my sister, ______is working in Beijing. A. which B. that C. whom D. who 22.In our factory there are 2,000 workers, two thirds of ____are women. A. them B. which C. whom D. who 23.You're the only person ______I've ever met ______could do it. A. who;/ B./; whom C. whom;/ D./; who 24.I lost a book, ______I can't remember now. A. whose title B. its title C. the title of it D. the title of that 25.Last summer we visited the West Lake, ______Hangzhou is famous in the world. A. for which B. for that C. in which D. what 26.I have bought such a watch _______ was advertised on TV. A. that B. which C. as D. it 27.I can never forget the day _______ we worked together and the day ______ we spent together. A. when; which B. which; when C. what; that D. on which; when ‎28.The way ______he looks at problems is wrong. A. which B. whose C. what D./ 29.This is the reason ______he didn't come to the meeting. A. in which B. with which C. that D. for which 30.This machine, ______for many years, is still working perfectly. A. after which I have looked B. which I have looked after C. that I have looked after D. I have looked after 31.The reason ______he didn't come was ______he was ill. A. why; that B.that;why C. for that;that D.for which;what 32.He is working hard, ______will make him pass the final exam. A.that B.which C.for which D.who 33.That is not the way ______I do it. A./ B.which C.for which D.with which 34.I have two grammars, ______are of great use. A. all of which B. either of which C. both of that D. both of which 35.I want to use the same tools _______used in your factory a few days ago. A. as was B. which was C. as were D. which ‎ ‎36.My neigh bours used to give me a hand in time of trouble, _______ was very kind of them. A. who B. which C. that D. it 37.This is the magazine _______ I copied the paragraph. A. that B. which C. from that D. from which 38.He is not such a man _______ would leave his work half done. A. that B. which C. who D. as 39. You can depend on whatever promise _______ he makes. A. / B. why C. when D. whose 40. Smoking, _______ is a bad habit, is, however, popular. A. that B. which C. it D. though 41. --- Did you ask the guard _______ happened? --- Yes, he told me all _______ he knew. A. what; that B. what; what C. which; which D. that; that 42. I shall never forget those years _______ I lived on the farm with the farmers, _______ has a great effect on my life. A. when; who B. that; which C. which; that D. when; which 43. The number of the people who _______ cars _______ increasing. A. owns; are B. owns; is C. own; is D. own; are 44. During the days ________, he worked as a servant at the Browns. A. followed B. following C. to follow D. that followed 45. Is oxygen the only gas _______ helps fire burn? A. that B. / C. which D. it 46. The clever boy made a hole in the wall, _______ he could see _____ was going on inside house. A. which; what B. through which; what C. through that; what D. what; that 47. Is _______ some German friends visited last week? A. this school B. this the school C. this school one D. this school where 48. John got beaten in the game, _______ had been expected. A. as B. that C. what D. who ‎ ‎49. I have bought two ballpens, _______ writes well. A. none of them B. neither of them C. neither of which D. none of which 50. All that can be eaten _______ eaten up. A. are being B. has been C. had been D. have been 参考答案及解析 1. A. which用作关系代词，在定语从句中作主语。 2．C. "和谁讲话”要说speak to sb. 本题全句应为Do you know the man whom I spoke to.。whom是关系代词，作介词to的宾语，可以省略。 3. D. where是关系副词，表示地点，在定语从句中作地点状语。 4. C. when是关系副词，表示时间，在定语从句中作时间状语。 5．A. which是关系代词，在从句中作forget的宾语。其他几个答案都不能作宾语。 6．C. 解析同第5题。 7. A. 解析见第3题。 8. A. 本句话的先行词应该是films,因此，关系代词that是负数概念，其谓语动词应用复述的被动语态have been shown。如果句中的one前面使用了定冠词the，则the one应该视为先行词。 9. A. “谈到某事物”应说talk about sth.。about是介词，其后要用which作宾语，不能用that。 10. A. with which是"介词+关系代词"结构,常用来引导定语从句.with有"用"的意思,介词之后只能用which,不能用that. with which在定语从句中作状语,即he is writing with a pen. 11. C. in front of which 即in front of a farmhouse. In front of which在从句中作状语. 12. D. with whom引导定语从句.with whom放在从句中即为:my father works with the engineer. 13. D. whose引导定语从句,在从句中作主语family的定语. 14. A. that引导定语从句,因为先行词是all,所以只能选用that引导. 15. D. the same……..as是固定用法, as引导定语从句时,可以作主语,宾语或表语.在本句话中,as作从句的主语. 16. D. such……… as是固定用法,as引导定语从句时,可以作主语,宾语或表语.在本 题中,as作表语. 17. B. as作关系代词可以单独用来引导非限制性定语从句。这时as所指代的不是主句中某个名词，而往往指代整个主句的含义。as在从句中可以作主语、宾语。从句可放在主句后，也可置于主句前。在本句中,as作宾语. 18. B. Li Ming enjoyed it very much是主句,with whom I went to the concert是定语从句.with whom放在从句中为:I went to the concert with Li Ming. 19. C. as引导定语从句时通常构成such…as或the same…as固定搭配，其中such和same修饰其后的名词，as为关系代词，指代其前的名词引导定语从句。 as在从句中可以作主语、表语或宾语。Such修饰单数名词时,要用such a……..,本题中such books, such直接修饰复数名词. 20. B. things和persons是先行词.当定语从句要修饰的先行词是既表示人,又表示物的名词时,其关系代词要用that. 21. D. who引导非限制性定语从句,who作从句的主语. 22. C. two thirds of whom 即:two thirds of the 2,000 workers. 23. D. 先行词person后有两个定语从句,第一个从句省略了关系代词whom.因为, whom作从句中met的宾语,可以省略.第二个从句who could do it.who在从句中作主语,不可省略. 24. A. whose title引导非限制性定语从句,whose title也可以说成the title of which 25. A. for which 引导定语从句,使用介词for,是来自于从句中的固定短语 be famous for "以……..而闻名". 26. C. 当先行词被such修饰时,引导定语从句的关系代词要用as. As在本从句中作主语. 27. A. 两个先行词the day都是表示时间的名词,但第一个空白处要填的关系词在从句中作状语,因此要用关系副词when. 第二个空白处要填的关系词在从句中作动词spent的宾语,因此要用关系代词which或that来引导定语从句. 28. D. 在way、distance、direction等词后的定语从句中，常用that来代替“in (或其他介词)+which”、when或where，而that常可省略。 29. D. for which在定语从句中作原因状语,可用why 来替代. 30. B. which I have looked after 构成一个非限制性定语从句. ‎ ‎31. A. The reason why… was that….已成为一种固定句型，这一句中的why和that不能随意换位，也不能将that改成because，尽管that这个词在译文中可能有 “因为”的含义。 32. B. 非限制性定语从句常用which引导,which表示前句话的整个含义. 33. A. 解释见28题. 34. D. 主句中的two表明不能选A.从句中的are表明不能选B. both of which用来引导非限制性定语从句. 35. C. as引导定语从句时通常构成such…as或the same…as固定搭配，其中such和same修饰其后的名词，as为关系代词，指代其前的名词引导定语从句。as在从句中可以作主语、表语或宾语。本题中as作从句的主语. 36. B. 非限制性定语从句常用which引导,which表示前句话的整个含义. 37. D. 38. D. 解析见35题. 39. A. he makes是定语从句, 从句前省略了关系代词that. 40. B. which is a bad habit 非限制性定语从句. 41. A. what happened是宾语从句. all 之后that he knew是定语从句.先行词是all,所以关系代词只能用that. 42. D. years是表示时间的名词,用when引导定语从句,是因为when在从句中作时间状语.第二个空选用which,引导一个非限制性定语从句. 43. C. 本句话的定语从句是who own cars. 其先行词是people,因此,定语从句的谓语动词要用复数的own。本句话主句的主语是The number of指“…..的数目”，是单数概念。因此，主句的谓语动词要用is。 44. D. that followed是定语从句，关系代词that在从句中作主语。 45. A. 先行词gas被only修饰，关系代词要用that，而不用which。 46. B. through which引导定语从句，through which即through the hole,在定语从句中作状语。What引导的是see的宾语从句，并作从句的主语。 47. B. 为便于理解，改写本句话：This is the school that some Germanfriends visited last week. 不难看出，作表语的the school是先行词。that引导了定语从句，因为that同时又作visited的宾语，所以被省略了。其它选项结构不对。 ‎ ‎48. A. 解释见35题。 49. C. 因为是two ballpens, 并且定语从句的谓语writes是单数概念。因此，C是正确选项。 50. B. 本句话中，主句的主语是all,为抽象概念。因此，其谓语应用单数的has been。关系代词that引导定语从句，并在从句中作主语。‎