高中英语It的用法专项练习题
- 格式:docx
- 大小:20.60 KB
- 文档页数:13
高考英语语法填空代词it的用法练习题30题1.It is important for us to learn English well.A.thatB.thisC.whatD.which答案:A。
本题考查it 作形式主语的用法。
“It is+形容词+for sb to do sth”是固定句型,it 作形式主语,真正的主语是后面的不定式短语“to learn English well”。
选项B“this”、C“what”、D“which”均不能在此处作形式主语。
2.We think it necessary to do exercise every day.A.thatB.thisC.whatD.which答案:A。
本题考查it 作形式宾语的用法。
“think it+形容词+to do sth”是固定句型,it 作形式宾语,真正的宾语是后面的不定式短语“to do exercise every day”。
选项B“this”、C“what”、D“which”均不能在此处作形式宾语。
3.It is said that he is very good at math.A.thatB.thisC.whatD.which答案:A。
本题考查it 作形式主语的用法。
“It is said that+句子”是固定句型,it 作形式主语,真正的主语是后面的that 引导的主语从句。
选项B“this”、C“what”、D“which”均不能在此处作形式主语。
4.We make it a rule to get up early.A.thatB.thisC.whatD.which答案:A。
本题考查it 作形式宾语的用法。
“make it a rule to do sth”是固定句型,it 作形式宾语,真正的宾语是后面的不定式短语“to get up early”。
选项B“this”、C“what”、D“which”均不能在此处作形式宾语。
高一it用法讲解及练习专项练习1.I like _______ in the autumn when the weather is clear and bright.A. thisB. thatC. itD. one2.—Shall we meet next week?—OK. We just make________ next Friday.A. oneB. itC. thatD. soA. whenB. thatC. sinceD. until4.It _______ to accomplish the return journey.A. coast us 15 daysB. spent 15days for usC. was 15 daysD. took us 15 days5. _______ from Beijing to London!A. How long way it isB. What long way is itC. How long way is itD. What a long way it is6. ________ i s reported in the newspaper, talks between the countries are making progress.A. ItB. AsC. ThatD. What7. ________ i s known to all that China is rich in natural resources.A. ItB. ThatC. WhatD. As8. _______ quite a few techniques to learn language well.A. It seems to haveB. There seem to beC. There seems to haveD. It seems to beA. who is heB. who he isC. who is itD. who itisA. thatB. whenC. beforeD. since11. _______ t hat I was watching TV when he came to see me.A. It happenedB. What happenedC. That happenedD. It was happened12.The chairman thought necessary to invite Professor Smith to speak at the meeting.A. thatB. itC. thisD. him13.The Foreign Minister said, " ________ our hope that the two sides will work towards peace."A. This isB. There isC. That isD. It is14. ________ i s reported in the newspaper that the terrible flood has caused a loss of 10 million yuan.A. ItB. ThisC. ThatD. AsA. decidingB. to decideC. of decidingD. decide16.Was________ that I saw last night at the corner?A. it youB. not youC. youD. thatyourselfA. whenB. beforeC. sinceD. that18. _______ t urn is_______ to clean the blackboard?A. Which... itB. Whose... itC. Which... thatD.Whose. .. that19.The seriously injured man has stopped breathing. will be no possibility of making him come to life.A. ItB. ThereC. ThatD. ThisA. it possibleB. it wasC. that being possibleD.possibleA. a ruleB. it a ruleC. a rule thatD. arule it is22.He moved to a new flat because is only five minutes' walk from the new flat to his office.A. itB. thisC. thatD. thereA. for... beforeB. not for... thatC. for... whenD. notfor... thenA. with whichB. thatC. whichD. whatA. to pick upB. of picking upC. to pickD.picking upA. learnedB. learnC. will learnD.would learnA. hasB. could haveC. haveD. hadA. sinceB. untilC. whenD.before29. ________ the 1500's _________ the first European explored the coast of California.A. It is not until... thenB. It was until... thatC. It's not until... whenD. It was not until... that30.I just wonder _________ that made them so depressed.A. why it didB. what they didC. how it wasD. whatit wasA. when... thatB. that... thatC. that... whenD.when... which32. _______ , they all went to the lake to swim.A. It was a hot dayB. Being a hot dayC. It being hotD. For it was a hot dayA. itB. thatC. thisD.which34.—_________ seems to be something wrong with the machine.—Yes,_______ got a lot of noise.A. It... it'sB. There... it'sC. I t... there'sD.There... there's35. _________ a certain doubt among the workers as to the necessity of the work.A. There areB. There isC. They areD. It isA. oneB. onceC. itD. herA. everythingB. itC. thatD.yourselfA. It is... There isB. There is... It isC. There is... There isD. It is...It isA. which... itB. that... itC. which... thatD. that...that40. ________ easy to do the repair. All you need is a hammer and some nails.A. You areB. That isC. There isD. It is Keys:1-5 CBCDD6-10 BABDB 11-15 ABDAB 16-20 ABDBD 21-25 BABBA26-30 ACDDD 31-35 DCABB 36-40 CBABD。
It的用法1. If you don’t know the new word, why don’t you________in the dictionary?A. look at itB. look after itC. look up itD. look it up答:D。
look up(在词典、参考书中)查寻。
副词与动词构成的词组与人称代词连用时,将人称代词放在中间。
A和B项与题童不符。
it指前文提到的事物。
2. There comes the bus, _________?A. B. does itC. doesn’t itD. isn’t itdoesn’t there答:C。
让指the bus。
3. That’s of great importance,_________?A. isn’t itB. isn’t thatC. isn’t thisD. is this答:A。
讧用以代替指示代词ths,that。
4. I saw no more than one camera left in that shop. Will you go and buy_________?A. someB. itC. anyD. one譬:B。
it为特指用陆,one为泛指。
5. ________ was a pity not to have gone to Shanghai.A. ThisB. ThereC. WhichD. It答:D。
it为形式主语,真正的主语为不定式。
6. —Have you heard the news about Tom?—No, what_________?A. is itB. it isC. are theyD. they are答:A。
it指 the news.7. ________ bad mumers to laugh at people when they are in trouble.A. It isB. There areC. That’sD. These are答:A。
高考英语专题之it的用法1.指代上文提到过的某物。
2.指代this和that。
3.指不知性别的婴儿或身份不明确的人。
4.指时间、距离、天气、气候、温度、日期或价值。
5.it代替不定式、动名词短语或名词性从句做形式主语。
(1)It is+adj.for /of sb. to do sth.(2)It is no wonder that...……不足为奇/并不奇怪(3)It seems/appears that...似乎/看来……(4)It looks/seems as if/as though...看起来/似乎/好像……(5)It happens that...碰巧……(6)It occurs to/comes to/strikes/hits sb. that...某人突然想起……(7)It is said/reported that...据说/据报道……(8)It is certain that...肯定……(9)It is well known/acknowledged that...众所周知……(10)It is no use/no good doing sth.做某事没用/没好处(11)It takes sb. some time to do sth.做某事花某人一些时间(12).It is clear (obvious, true, possible, certain) that….“清楚(显然、真的、肯定)”(13).It is important (necessary, right, strange, natural…) that…(虚拟should+动词原形)(14).It is suggested (ordered…) that…(虚拟should+动词原形)(16). It doesn’t matter whether………不重要,没关系(17).It is a pity/shame that...真可惜……6.it做形式宾语(1)主语+think/believe/suppose/consider/feel/make/keep...+it+adj./n.+for/of+sb.to do sth./that从句(2)主语+think/believe/suppose/consider/feel/make/keep...+it+unless/no use/no good...doing sth.7.其他与it相关的常用短语和句型(1)I take it that you don't agree with me.我想你不同意我的意见。
高中英语语法:It用法专项练习30题(word版可编辑修改)编辑整理:尊敬的读者朋友们:这里是精品文档编辑中心,本文档内容是由我和我的同事精心编辑整理后发布的,发布之前我们对文中内容进行仔细校对,但是难免会有疏漏的地方,但是任然希望(高中英语语法:It用法专项练习30题(word版可编辑修改))的内容能够给您的工作和学习带来便利。
同时也真诚的希望收到您的建议和反馈,这将是我们进步的源泉,前进的动力。
本文可编辑可修改,如果觉得对您有帮助请收藏以便随时查阅,最后祝您生活愉快业绩进步,以下为高中英语语法:It用法专项练习30题(word版可编辑修改)的全部内容。
1。
I like_____________in the autumn when the weather is clear and bright.A。
this B。
that C. it D。
one[解析] C。
句中like为及物动词,后面需要跟宾语.而like之后不可直接接从句作宾语。
it可用于某些动词(hate,appreciate…)和介词之后作笼统宾语。
2。
He was nearly drowned once。
When was_____________?_____________ was in 1998 when he was in middle school.A. that; ItB. this; ThisC. this; It D。
that; This[解析]A。
第一空用that指代上文提到的事情;第二空用it指代第一空的that3. The Parkers bought a new house but_____________will need a lot of work before they can move in.A. they B。
it C。
one D。
which[解析] B此处it指代前面出现的a new house. it指代上文提到的同一事物,为特指;而one通常指代同类事物中的某一个。
高考英语语法填空代词it的用法单选题30题1.It's a beautiful day. ____ is perfect for a picnic.A.ItB.ThatC.ThisD.One答案:A。
本题中it 作人称代词指代天气,B 选项that 一般用于指代较远的事物,C 选项this 一般用于指代较近的事物,D 选项one 一般用于指代可数名词单数。
2.I love my new phone. ____ has a great camera.A.ItB.ThatC.ThisD.One答案:A。
这里it 作人称代词指代my new phone,B 选项that 一般不用于指代上文提到的事物,C 选项this 一般用于指离说话人较近的事物,D 选项one 指代同类事物中的一个。
3.The cat is very cute. ____ likes to play with balls.A.ItB.ThatC.ThisD.One答案:A。
it 作人称代词指代the cat,B 选项that 一般不用于指代动物,C 选项this 一般用于指离说话人较近的事物,D 选项one 不能指代动物。
4.The baby is sleeping. ____ is so peaceful.A.ItB.ThatC.ThisD.One答案:A。
it 作人称代词指代the baby,B 选项that 一般不用于指代人,C 选项this 一般用于指离说话人较近的事物,D 选项one 不能指代人。
5.The book is interesting. ____ tells a great story.A.ItB.ThatC.ThisD.One答案:A。
it 作人称代词指代the book,B 选项that 一般用于指代较远的事物,C 选项this 一般用于指离说话人较近的事物,D 选项one 一般用于指代可数名词单数。
高一英语名词性从句中it作形式主语练习题30题答案解析版1. It is important to learn English well.答案:无选项。
解析:在这个句子中,“It”作形式主语,真正的主语是“to learn English well”。
“It is + 形容词+ to do sth.”是一个常用的句型,表示“做某事是……的”。
例如:It is difficult to solve this problem. (解决这个问题是困难的。
)2. It is no use crying over spilt milk.答案:无选项。
解析:“It is no use doing sth.”是固定句型,“It”作形式主语,真正的主语是“crying over spilt milk”,意思是“为打翻的牛奶哭泣是没有用的”。
比如:It is no use regretting what has happened. 后悔已经发生的事是没用的。
)3. It is a pity that you missed the party.答案:无选项。
解析:“It is a pity that...”是常见句型,“It”作形式主语,“that you missed the party”是真正的主语从句。
像这样:It is a shame that he failed the exam. 他考试不及格真是件羞愧的事。
)4. It seems that he is very busy.答案:无选项。
解析:“It seems that...”表示“似乎……”,“It”作形式主语,“that heis very busy”是真正的主语从句。
例如:It seems that she knows the truth. 似乎她知道真相。
)5. It happened that I was out when he called.答案:无选项。
高中英语真题:it用作形式主语代替动名词主要用于哪些句式it用作形式主语代替动名词的用法主要见于以下句式:1. It is no use (no good, fun, great fun, a new experience, a great ho nour, etc) doing sth。
如:It is no good talking. 空谈是没有用的。
It’s fun working for him. 为他工作很有意思。
It’s great fun sailing a boat. 扬帆驾舟十分有趣。
It’s no use shouting at him—he’s deaf. 向他叫喊是没有用的——他耳聋。
It has been a great honour your coming to visit us. 你来看望我们是极大荣幸。
2. It is good (nice, useless, interesting, pleasant, tiring, etc) doing sth。
如:It is useless speaking. 光说没有用。
It was pleasant sitting there. 坐在那里很愉快。
It’s so nice sitting here with you. 和你坐在一起真是愉快。
It’s good hearing English spoken. 听到人讲英语,我很高兴。
It’s terribly tiring working late like this. 这样干到深夜是非常累人的。
3. it is worth while doing sth。
如:It’s worth while doing the work. 这项工作值得做。
Do you think it’s worth while quarrelling with me? 你认为和我吵值得吗?4. 其他句式。
中学英语It的用法专项练习题一1. Was it during the Second World War_____ he died?A.thatB.whileC.in whichD.then2. Is ____ necessary to complete the design before National Day?A.thisB.thatC.itD.he3. I don't think ____ possible to master a foreign language without much memory work.A.thisB.thatC.itsD.it4. Does ______ matter if he can't finish the job on time?A.thisB.thatC.heD.it5. It was not _____ she took off her glasses _____ I realized she was a famous film star.A.when, thatB.until, thatC.until, thatD.when, then6. I was disappointed with the film. I had expected ______ to be much better.A.thatB.thisC.oneD.it7. It was not until 1920 ______ regular radio broadcasts began.A.whileB.whichC.thatD.since8. ______is a fact that English is being accepted as an international language.A.ThereB.ThisC.ThatD.It9. It was only when I reread this poems recently _____ I began to appreciate their beauty.A.untilB.thatC.thenD.so10. I hate_____when people talk with their mouths full.A.itB.thatC.theseD.them11. It is the ability to do the job _____ matters not where you come from or what you are.A.oneB.thatC.whatD.it12. I like ___ in the autumn when the weather is clear and bright.A. thisB. thatC. itD. one13. ―Do you like ___ here?―Oh, yes. The air, the weather, the way of life. Everything is so nice.A. thisB. TheseC. ThatD. it14. We needed a new cupboard for the kitchen. So Peter made ___ from some wood.A. itB. OneC. HimselfD. another15. The foreign Minister said, " _____ our hope that the two sides will work towards peace."A. This isB. There isC. That isD. It is16. _____ is reported in the newspaper, talks between the two countries are making progress.A. ItB. AsC. ThatD. What17. ― How often do you eat out?― ________, but usually once a week.A. Have no ideaB. It dependsC. As usualD. Generally speaking18. We wanted to get home before dark, but it didn't quite _____ as planed.A. make outB. turn outC. go onD. come up19. ― What do you want to do next? We have half an hour until the basketball game.―________. Whatever you want to do is fine with me.A. It just dependsB. It's up to youC. All rightD. Glad to hear that20. It was ____ back home after the experiment.A. not until midnight did he goB. until midnight that he didn't goC. not until midnight that he wentD. until midnight when he didn't go练习题二1. It ___ for this reason ___ her uncle moved out of New York.A. is ... whichB. was ... whyC. was ... thatD. were ... How2. It was ___ he said at the meeting __ disappointed me.A. what.., thatB. that.., thatC. what.., whatD. that.., what3. ---Wasn’t it Dr. Li who spoke to you just now?--- ______ .A. I didn't know he wasB. Yes, he didC. No, he didn'tD. Yes, it was4. Was it during the Second World War____ he died?A. thisB. thenC. thatD. while5. I don’t think _____ possible to master a foreign language without much memory work.A. thisB. itC. thatD. its6. Does ____ matter if he can't finish the job on time?A. itB. thisC. thatD. he7. Tom’s mother kept telling him that he should work harder, but __didn’t help.A. heB. whichC. sheD. it8. Was ___ in 1998 ___ your teacher graduated from university?A. that.., thatB. it... whichC. it... thatD. it... when9. He felt ___ duty to work for human rights and progress.A. it hisB. hisC. that is aD. that is his10. ___ is no good ___ without doing anything.A. This... talkingB. It... to speakC. That... to sayD. It... talking11. All the children except my partner ___ late because of traffic jam.A. isB. areC. wasD. has been12. Your new clothes fit you, but mine ___ me.A. don’t fitB. doesn’t fitC. don’t fit forD. aren’t fit练习题三1. It was this village ___ I was brought up.A. whereB. thatC. on whichD. which2. It was in this village ___ I was bought up.A. whereB. thatC. on whichD. which3. Can it be in the drawer ___ you put your passport?A. whereB. in whichC. thereD. that4. It was July 1, 1997 ___ saw the return of Hong Kong to the motherland.A. thatB. whenC. whichD. in which5. It is two years __ I joined the army.A. beforeB. sinceC. thatD. after6. It was two years ___ I joined the army.A. beforeB. sinceC. thatD. after7. --- Was it under the tree ___ you were away talking to a friend?--- Sure. But when I got back there, the bike was gone.A. thatB. whereC. whichD. while8. --- Why don’t we take a little break ?--- Didn’t we just have ____ ?A. itB. thatC. one D 。
this9. It was not until 1920 ____ regular radio broadcast began.A. whileB. whichC. thatD. since10. ___ is the fact that English is being accepted as an international language.A. ThereB. ThisC. ThatD. It11. It was about 600 years ago ___ first clock with a face and an hour hand was made.A. thatB. untilC. beforeD. when12. I hate ____ when people talk with their mouths full.A. itB. thatC. theseD. them13. It was only when I reread his poems recently ____ I began to appreciate their beauty.A. untilB. thatC. thenD. so14. It is the ability to do the job ____ matters not where you come from or what you are.A. oneB. thatC. whatD. it15. The Parkers bought a few house but __ will need a lot of work before they can move in.A. theyB. itC. oneD. which16. ____ no need for us to discuss the problem again since it has already been settled.A. It hasB. There hasC. It isD. There is17. Was it in 1969 __ the American astronaut succeeded ___landing on the moon.A. when; onB. that; onC. when; inD. that; in18. Was ___ that I saw last night at the concert?A. it youB. not youC. youD. that yourself19. ____ was in 1979 ___ I graduated from the university.A. That; thatB. It; thatC. That; whenD. It; when20. What a pity my new computer doesn’t work! ____ must be something wrong with it.A. ItB. ThereC. ThisD. That21. I like ____ in the autumn when the weather is clear and bright.A. thisB. thatC. itD. one22. Someone is knocking at the door, but who can ___ be?A. oneB. heC. sheD. it23. A knock on the door made him look up. But ___ was only the manager.A. thisB. thatC. sheD. it24. Someone is ringing the doorbell. Go and see ____ .A. who is heB. who he isC. who is itD. who it is25. Is ___ necessary to complete the design before National Day?A. thisB. thatC. itD. he26. Does ___ matter if he can’t finish the job on time?A. thisB. thatC. heD. it27. It worried her a bit ___ her hair was turning grey.A. whileB. thatC. ifD. for28. They have made __ a rule __in the room.A. this; not to smokeB. it; smokingC. it; to not smokeD. it; not to smoke一.单项选择练习四1.It was at the gate ____ he told me the news.A. thatB. whatC. whichD. when2.Is ____necessary to tell his father everythingA. itB. thatC. whatD. he3.Was it in this palace ____ the last emperor died?A. thatB. in whichC. in whereD. which4.Is ____ possible to fly to the moon in a spaceship?A. nowB. manC. thatD. it5.Was it during the Second World War ____he died?A. thatB. whileC. in whichD. then6.Is ____necessary to complete the design before National Day?A. thisB. thatC. itD. he7.I don't think ____possible to master a foreign language without much memory work.A. thisB. thatC. itsD. it8.Does ____matter if he can't finish the job on time?A. thisB. thatC. heD. it9.It was not ____she took off her dark glasses ____ ,I realized she was a famous film star.A. when; thatB. until; thatC. until; whenD. when; then10.Tom?s mother kept telling him that he should work harder, but ____didn?t help.A. heB. whichC. sheD. it11.____is a fact that English is being accepted as an international language.A. ThereB. ThisC. ThatD. It12. Is ________ possible to fly to the moon in a spaceship?A.now B.man C.that D.it13.Our food and service are better than ________ used to be.A.it B.we C.they D.them14.________ appears to me ________ the report must be truth.A.That; it B.It; that C.It; it D.That; that15.He feels ________ duty to help others.A.that he B.that his C.it he D.it his16.Take ________ easy. The roads are icy.A.it B.them C.us D.you17.The TV sets made in China are much better than ________ in Japan. A.that B.those C.them D.It18.—— Have you found the bike you lost yesterday?—— Yes, I've found ________ already.A.it B.that C.the one D.that one19.—— I'm looking for a flat.—— Would you like ____ with ____ garden?A.it; the B.it; a C.one; a D.one; the20.________ was ________ who I met in the museum this morning.A.It; him B.It; he C.That; he D. That; him21.It was in the rice fields ________ we had our League meeting. A.where B.that C.in which D.on which22.________ you come to the party so late?A.Why is it B.Why it isC.Why it is that D.Why is it that23.—— Were all three people in the car injured in the accident—— No, ___ only the two passengers ___ got hurt.A.they were; that B.there was; thatC.it was; who D.there are; who24.I don' t think ________ possible to master a foreign language withoutmuch memory work .A.this B.that C.its D.it25.It was not ________ she took off her glasses ________ I realized she was a famous film star.A. when; thatB. until; thatC. until; whenD. when; then26.It was not until 1920 ____ regular radio broadcasts began.A.while B.which C.that D.since27.________ is a fact that English is being accepted as an international language. A.There B.This C.That D.It28.It was about 600 years ago ________ the first clock with a face and an hour hand was made.A.that B.until C.before D.when29.It was only when I reread his poems recently ____ I began to appreciate their beauty. A.until B.that C.then D.So30.I hate ______ when people talk with their mouths full.A.it B.that C.these D.them31.—— Why don't we take a little break? —— Didn't we just have ________ ? A.it B.that C.one D.this32.Was it during the Second World War ____ he died?(MET88)A.that B.While C.in which D.Then33.Is ____ possible to fly to the moon in a spaceship?(MET88)A.now B.that C.it D.Man34.I don't think ___ possible to master a foreign language without much momory work.(MET90)A.This B.that C.its D.It35.___ is a fact that English is being accepted as an international language.(NMET95)A.There B.This C.That D.It36.It was about 600 years ago ___ the first clock with face and an hour hand was made.(NMET97)A.that B.until C.before D.when37.____computers play such an important part in our daily life?A.Why it is that B.Why is it thatC.Why was it that D.Why is it38. Was it during the Second World War _____he died?A. thatB. whileC. in whichD.then39. Is ____ necessary to take off our shoes when we enter the lab?A. everyoneB.thisC.herD.it40. Is ____ possible to fly to the moon in a spaceship?A.nowB.thatC.itD.man41. I don?t think ___ possible to master a foreign language without much memory work. A.this B.that C.its D.it42. She heard of a terrible noise, ___ brought her heart into her mouth.A.itB.whichC.thisD.that43. Alice received an invitation from her boss, ____ came as a surprise.A.itB.thatC.whichD.he44. Does ____ matter if he can?t finish the job on time?A.thisB.thatC.heD.it45.Tom?s mother kept telling him that he should work harder, but ____ didn?t help. A.he B.which C.she D.it46.The weather turned out to be very good, ___ was more than we could expect. A.what B.which C.that D.it47.____is a fact that English is being accepted as an international language.A.ThereB.ThisC.ThatD.It48.I hope there are enough glasses for each guest to have _____.A.itB.thoseC.themD.one49.It was about 600 years ago___the first clock with a face and an hour hand was made.A.thatB.untilC.beforeD.when50.I hate ____ when people talk with their mouths full.A.itB.thatC.theseD.them51.It was only when I reread his poems recently____ I began to appreciate their beauty.A.untilB.thatC.thenD.so52.It is the ability to do the job ____ matters not where you come from or what you are. A.one B.that C.what D.it53.It ____ you that ____ to blame.A.is;isB.is; areC.are;areD.are;is54.Was_____that I saw last night at the concert?A.it youB.not youC.youD.that you55.____ electricity plays such an important part in our life?A.Why is it thatB.Why is itC.Why it is thatD.Why is that56.It was ____ he said _____ disappointed me.A.what;whatB.that;thatC.what;thatD.that;what57.It was in the lab ___ was taken charge of by Professor Harris ___ they didthe experiment.A.which; thatB.that; whatC.whom; thatD.which; where58.Many people now make a rule to buy cards for their friends before Christmas.A.themselvesB.itC.thatD.this59.Someone is at the door, who is ?A.thisB.thatC.itD.he60.—It is raining cats and dogs.A.So it isB.So is itC.Neither it isD.Neither is it练习一:1-5 ACDDB 6-10 DCDBA 11-15 ACDBD 16-20 BBBBC练习二 1.CADC 5. BADC 9. ADBA练习三 1.ABDAB 6.ADDCD 11.AABBB 16.DDABB 21.DDDDC 26.DBD练习四:1-30 ABADA CDDBD DDCBD ABACA BDADB CDABA31-60 CACDD AB ADC DBCDD BDDAA BBBAA CABCA。