中考复习专题(七)阅读理解题
教学目标:
了解阅读理解题的特点和类型,掌握这类题的解题思路,学会如何解阅读理解题;通过解阅读理解题,巩固学生的数学基础知识、提高阅读能力,培养学生的数学意识和数学综合应用能力,进一步提高学生的数学思维能力和创新意识,为学生的后续学习和终身学习打好基础.
教学重、难点:对阅读理解题的阅读材料的理解,对题中的错综复杂关系的梳理,对新知识和新信息的接受和处理.
教学过程:
一、题型归析
阅读理解题是近几年新出现的一种新题型,这种题型特点鲜明、内容丰富、超越常规,源于课本,高于课本,不仅考查学生的阅读能力,而且综合考查学生的数学意识和数学综合应用能力,尤其侧重于考查学生的数学思维能力和创新意识,此类题目能够帮助学生实现从模仿到创造的思维过程,符合学生的认知规律.阅读理解题一般由两部分组成:一是阅读材料;二是考查内容.它要求学生根据阅读获取的信息回答问题.提供的阅读材料主要包括:一个新的数学概念的形成和应用过程,或一个新数学公式的推导与应用,或提供新闻背景材料等.考查内容既有考查基础的,又有考查自学能力和探究能力等综合素质的.涉及到的数学知识很多,几乎涉及所有中考内容.是中考的热点题目之一,今后的中考试题有进一步加强的趋势.
二、典型例题解析
【例1】读一读:式子“1+2+3+4+5+…+100”表示从1开始的100个连续自然数的和.由于上述式子比较长,书写也不方便,为了简便起见,我们可将“1+2+3+4+5+…+100”表示为,这里“”是求和符号.例如:“1+3+5+7+9+…+99”(即从1开始的100以内的连续奇数的和)可表示为;又如“13+23+33+43+53+63+73+83+93+103”可表示为.
同学们,通过对以上材料的阅读,请解答下列问题:
①2+4+6+8+10+…+100(即从2开始的100以内的连续偶数的和)用求和符号可表示为;
②计算:=(填写最后的计算结果).
【分析】本题就是先给读者提供全新的的阅读材料,介绍了求和符号“”的意义,这是学生没有碰到过的新知识,只有通过阅读理解它的意义,才能正确解答下面有关问题.求和符号的下面和上面的数字分别表示求和加数的首、尾数字序数,求和符号右边的代数式表示求和加数的性质.
解:(1);(2)50.
规律总结
本题是一道在初中和高中知识的衔接点上命题的代数阅读理解题,学生只有正确阅读理解求和符号“”的意义、书写格式等知识,才能迁移运用,再发散开放.
【例2】阅读下列材料,并解决后面的问题:在锐角△ABC中,∠A、
∠B、∠C的对边分别是a、b、c.过A作AD⊥BC于D(如图),则
sinB=,sinC=,即AD=csinB,AD=bsinC,于是csinB=bsinC,
即.同理有,.所以………(*)
即:在一个三角形中,各边和它所对角的正弦的比相等.
(1)在锐角三角形中,若已知三个元素a、b、∠A,运用上述结论(*)和有关定理就可以求出其余三个未知元素c、∠B、∠C,请你按照下列步骤填空,完成求解过程:
第一步:由条件a、b、∠A∠B;
第二步:由条件∠A、∠B∠C;
第三步:由条件c.
三、诊断自测
1.计算机是将信息转换成二进制数进行处理的,二进制即“逢二进一”,如(1101)表示二进制数,转换为十进制形式是,那么将二进制(1111)转换为十进制形式是数()A.8B.15C.20D.30
2.在日常生活中如取款、上网等都需要密码.有一种用“因式分解”法产生的密码,方便记忆.原理是:如对于多项式,因式分解的结果是,若取x=9,y=9时,则各个因式的值是:(x-y)=0,(x+y)=18,(x2+y2)=162,于是就可以把“018162”作为一个六位数的密码.对于多项式,取x=10,y=10时,用上述方法产生的密码是:(写出一个即可).
3.阅读材料:设一元二次方程的两个根为,,则两根与方程系数之间有如下关系:.根据该材料填空:
已知,是方程的两实数根,则的值为.
4.在5.12汶川大地震发生以后,全国人民众志成城,某首长到帐篷厂视察,布置赈灾生产任务,下面是首长与厂长的一段对话:
首长:为了支援灾区人民,组织上要求你们完成12000顶帐篷的生产任务.
厂长:为了尽快支援灾区人民,我们准备每天的生产量比原来多一半.
首长:这样能提前几天完成任务?
厂长:请首长放心!保证提前4天完成任务!
根据两人的对话,问该厂原来每天生产多少顶帐篷?
Researchers(研究者)haveannounced(宣布)theresultoftwostudiesonthehealtheffectsofthedrugaspirin(阿斯匹林).Onestudyshowsaspirincansharplyreducethechancethatahealthy,oldermanwillsufferfromaheartattack(心脏病).
Thestudyofferedtwonewresultsfromearlierfindings.Itsaidtakingoneaspirinpilleveryotherdayhelpedonlyhealthymenovertheageoffifty.Italsosaidaspiringavethegreatestprotectionagainstheartattackstomenwithlowbloodcholesterol(胆固醇)levels.
EarlierintheUnitedStatesbeganamajoraspirinstudyintheearly1980s.Itincluded22,000healthymendoctors.Allwerebetweentheagesoffortyandeighty-four.Morethan11,000ofthedoctorstookaharmlesspillthatcontainednodrug.Themendidnotknowwhichkindofpilltheyweretaking.
Thedoctorswhotookaspirinsuffered44%fewerheartattacksthanthosetakingtheharmlesspill.139menwhotookaspirinsufferedfromheartattacks.Tenofthemdied.239menwhodidnottakeaspirinsufferedfromheartattacks.Twenty-sixofthemdied.
Theresearcherssaidthedoctors’studyprovidesclearproofthattakingaspirincanpreventafirstheartattackinhealthy,oldermen.Theysaid,however,theresultdoesnotmeaneverymanovertheageoffiftyshouldtakeaspirin.Theysaidaspirincouldn’thelpmenwhodonoteathealthyfoods,whosmokecigarettesandwhoarefat.Theresearcherssaidmenwhothinktheywouldbehelpedbytakingaspirinshouldtalkwiththeirdoctorsfirst.
1.Thepassagetellsusthatthenewuseofaspirinis______.
A.totreatheartdisease
B.toreducepainwhileonesuffersfromaheartattack
C.tohelpoldpeopletobemorehealthy
D.toreducethechanceofaheartattackinoldmen
2.Aspirincanhelpthosewho______.
AworkasdoctorsB.areunder40yearsold
C.arefatandsmokecigarettesD.areolderandhealthy
3.Atlasttheresearchersadvisedustotakeaspirin______.
A.withcareB.asmuchaswelike
C.everydayD.onlyconsideringtheage
4.Fromtheexperimentwecanconcludethatabout_____ofpeoplewhosufferedfromheartattackswithoutaspirindied.
A.7%B.11%C.19%D.44%
Passage24
Itseemstobestrangetoyouthereisablindspot(盲点)ontheeyes.Hereisaninterestingexperiment(实验)thatcanmakesomethingdisappear,whenoneeyeisopen.
MakeacardaboutthesizeofapostcardandwritetwoEnglishlettersLandRonit,LontheleftandRontheright.First,holdthecardabout80cmawayandyouseeboththeletters.ThencloseyourrighteyeandlookattheletterRonlywithyourlefteye.Andnow,asyoumovethecardslowlytowardsyou,you’llfindtheletterLdisappearing.Butifyoumovethecardnearertoyourface,theletterwillbeseenagain.Nowdothesameexperimentwithyourlefteyeclosed,you’llfindtheletterRdisappearing.
Whydoestheletterdisappear?Itisbecausethereisablindspotontheeye.Whentheimage(影像)oftheletterfallsontheblindspot,itwon’tbeseen.Thatiswhyeitherofthelettersdisappears.
1.Thewriterofthepassagethinksthat_____thereisablindspotontheeye.
A.fewpeopleknowB.nooneknowsC.mostpeopleknowD.allthepeopleknow
2.Theword“disappear”inthepassagemeans________inChinese.
A.驱散B.消散C.消失D.遗失
3.YoufailtoseetheletterLintheexperimentbecause___________.
A.youreyesarepoorB.itsimagefallsontheblindspot
D.yourlefteyeisnotopenC.youmoveitclosetoyoureye
4.Inwhichorder(顺序)shouldyoudotheexperiment?
①Holdthecard②Movethecardnearer③Closeyourrighteye
④WritetwoEnglishletters⑤LookattheletterR⑥Makeacard
A.④⑥①②③⑤B.①③⑥④⑤②C.⑥①④③②⑤D.⑥④①③⑤②
5.Thepassagemainly(主要)tellsus_______.
A.howtofindtheblindspotB.aninterestingexperiment
C.wheretheblindspotisD.thereisblindspotontheeye
Passage25
Differentweathermakespeoplefeeldifferent.Itinfluences(影响)health,intelligence(智力)andfeelings.
InAugust,itisveryhotandwetinthesouthernpartoftheUnitedStates.Peopletherehavehearttroubleandotherkindsofhealthproblemsduringthismonth.IntheNortheastandtheMiddleWest,itisveryhotatsometimesandeverycoldatothertimes.PeopleinthesestateshavemorehearttroubleaftertheweatherchangesinFebruaryorMarch.
Theweathercanalsoinfluenceintelligence.Forexample,ina1983reportbyscientists,IQ(智商)ofagroupstudentswereveryhighwhenaverystrongwindcame,butafterthestrongwind,theirIQwas10%below.Thewindcanhelppeoplehavemoreintelligence.Veryhotweather,ontheotherhand(另一方面),canmakeitlower.StudentsinmanyschoolsoftheUnitedStatesoftengetworseonexamsinthehotmonthsoftheyear(JulyandAugust).
Weatheralsohasastronginfluenceonpeople’sfeelings.Wintermaybeabadtimeforthinpeople.Theyusuallyfeelcoldduringthesemonths.Theymightfeelunhappyduringcoldweather.Butfatpeoplemayhaveahardtimeinhotsummer.Atabout18C,peoplebecomestronger.
Lowairpressure(气压)maymakepeopleforgetful.Peopleleavemorebagsonbusesandinshopsonlow-pressuredays.Therearea“goodweather”forwordandhealth.Peoplefeelbestatatemperatureofabout18centigrade(摄氏度).
Areyoufeelingsad,tired,forgetful,orunhappytoday?Itmaybetheweather’sproblem.
1.____canhaveabadeffect(作用)onhealth.
A.HotandwetweatherB.Goodweather
C.WarmweatherD.Highintelligence
2.Peoplemayhavemoreintelligencewhen_____comes.
A.arainB.veryhotweather
C.astrongwindD.lowairpressure
3.Lowairpressuremaymakepeople_______.
A.forgetfulB.sadC.angryD.tired
4.In“goodweather”of18centigrade,_______.
A.peopleareveryforgetfulB.peoplecan’tdotheirworkwell
C.thinpeoplefeelcoldD.peopleareinbetterhealth
5.Thewriterwantstotellusthat_______.
A.hotandcoldweatherinfluencesallpeopleinthesameway
B.weatherinfluencespeople’slives
C.IQneverchangesduringweatherchanges
D.Thereisagoodkindofweatherforpeople’sworkandhealth
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