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doinganexperimenttongscrucibledissolvesolid/liquid/gasbalanceBunsenburnertesttube1.(a)Waterexistsasasolid,aliquidandagas.(b)Waterexistsasasolidandaliquidonly.2.(a)Whenyouheatametal,itexpands.(b)Whenyouheatametal,itcontracts.Guess,listenandchecktheanswer.3.(a)Steelisamixtureofironandothersubstances.(b)Steelisamixtureofironandoxygen.4.(a)Two-thirdsoftheearth’ssurfaceiswater.(b)50%oftheearth’ssurfaceiswater.5.(a)Thedistanceofthesunfromtheearthis25,5000kilometers.(b)Thedistanceofthesunfromtheearthis150,500,500kilometers.6.(a)Theearthis4.6millionyearsold.(b)Theearthis4.6billionyearsold.7.(a)Theearthistwiceaslargeasthemoon.(b)Theearthisforty-ninetimeslargerthanthemoon.Putthewordsinpairsorgroups.1234air–gas-oxygencontract-expandearth–sun-moongas–liquid-solidcontractairearthgasliquidoxygenmoonsolidsunexpandAnswerthesequestions.1.Whichoftheabovearenatural?Electricity,iron,somemetalsandairarenatural.2.Whichareman-made?Steel,somemetalsandglassareman-made.electricityironmetalsteelairglass3.Whichcanbeboth?Electricityandsomemetals(alloysforexample)canbeman-madeandoccurnaturally.1.Whenyouheatametal,itexpands.expandvi.膨胀，扩张Example:1.Thepetalsofmanyflowersexpandinthesunshine.许多花的花瓣在阳光中绽放。反义词contractvi.收缩n.合同Example:1.Theheatcontractedthewoolensweeter.高温让羊毛衣缩小了。2.I'mundercontracttoteachhereforoneyear.我按照聘约要在这里教一年书。2.Steelisamixtureofironandothersubstances.mixturen.混合物Example:1.Themixtureofdrinksmademefeelbad.mixv.混合mixAwithBsubstancen.物质Example:1.Bewareofwhatyoudowiththisdangeroussubstance.你处理这些危险品时，可要当心。Doexercises5and6onpage92.1.原级比较：两者程度相同。用句型as+形容词/副词+as表示,否定名式为:notas/so+形容词/副词as。Example:1.Dickisastallashisbrother.2.Tomspeaksasquicklyashiscousin.3.Ihaveneverseenapersonas/socleverasheis.形容词和副词比较等级的用法2.比较级：A.表示A超过B。此时用形容词和副词的比较级。Example:1.Ourclassroomisbrighterthanyours.2.Dogsrunfasterthanrabbits.3.Idon’tthinkmathismoreimportantthanphysics.B.表示A不如B。句型：less+形容词/副词原级。Example:1.Rabbitsranlessfastthandogs.2.Jennyislesscleverthanhersister.3.Itrainslessoftenhereinautumnthaninspring.3.形容词和副词比较级的特殊用法A.越来越……比较级+and+比较级Example:1.Youaregrowingtallerandtaller.2.Englishisbecomingmoreandmoreimportant.B.越……，越……the+比较级+the+比较级Example:1.Themorecarefulyouare,thebetteryouwilldointheexam.2.Themoreyoupractice,themorefluentlyyouwillspeak.C.表示两者之中比较……的一个，用of引导，比较级前加上the。Example:1.Jackisthetallerofthetwobrothers.2.Thisisthebiggerofthetworooms.D.nomorethan表示“只；不超过；不多于”，相当于only。Example:1.Hiswholeschooladdeduptonomorethanoneyear.2.Shehasnomorethanoneyuaninherpocket.E.nomore…than表示“……一样不……”；而notmore…than则表示“不像……那样”，相当于“notso…as”。Example:1.Hsisfeelingnobetterthanyesterday.他觉得不比昨天好多少。1.Sheisnotmoregenerousthanheryoungersister.她不如她妹妹那样慷慨大方。2.Sheisnotsogenerousasheryoungersister.相当于：F.nolessthan表示“多达，……那样多;至少,起码”,相当于asmuch/manyas,蕴含这个数是大的；而notlessthan表示“不少于”,不强调这个数的大小,只说明数据本身。Example:Ihavenolessthantendictionaries.我起码有10本字典。（至少）Ihavenotlessthantendictionaries.我有的词典不少于10本。（不含“我的词典多”的意思，只说明一个事实。）G.noless…than表示“不比……差；与……同样地”，相当于“as…as”。Example:Sheisnolessbeautifulthanhersister.她和她的姐姐一样漂亮。H.不用比较级的形容词如：senior,junior,superior,inferior等。Example:1.Heisthreeyearsseniortome.他比我大三岁。2.Yourknowledgeofelectronicsismuchsuperiortomine.你对电子学的知识远远超过我。I.比较级的修饰语。通常为副词或短语，置于比较级前面，说明比较级的程度。alittle,little,abit,bit,alot,agreatdeal,much,far,rather,slightly,byfar,even,still,nearly,almost,any,just,(…)times等。Example:1.Themoonismuchsmallerthantheearth.2.Theresultoftheexperimentturnedouttobeevenbetterthanexpected.3.Speakabitmoreslowly,please.4.Theoutputofthepapermillisthreetimeshigherthanitwaslastyear.Makesentencesaboutthecomparativesizesofthepairs.Usethewordsinthebrackets.YangtzeRiverSonghuaRiver6,300kilometers2,309kilometerslong/lengthExample:A:TheYangtzeRiverisaboutthreetimesaslongastheSonghuaRiver.B:TheYangtzeRiverisaboutthreetimeslongerthantheSonghuaRiver.C:TheYangtzeRiverisaboutthreetimesthelengthoftheSonghuaRiver.WinterinHarbinWinterinBeijing-20℃-5℃(cold/coldness)A:WinterisfourtimesascoldinHarbinasinBeijing.B:WinterisfourtimescolderinHarbinthaninBeijing.C:WinterinHarbinisfourtimesthecoldnessofinBeijing.MountTaiMountQumolangma1521m8848m(high/height)A:MountQumolangmaisaboutsixtimesashighasMountTai.B:MountQumolangmaisaboutsixtimeshigherthanMountTai.C:MountQumolangmaisaboutsixtimestheheightofMountTai.myhousemyaunt’shouselarge/size80squaremeters160squaremetersA:Myaunt’shouseistwiceaslargeasmyhouse.B:Myaunt’shouseistwicelargerthanmyhouse.C:Myaunt’shouseistwicethesizeofmyhouse.LilyweighsTomweighs45kilograms90kilogramsheavy/weightA:TomweighsovertwiceasheavyasLily.B:TomisovertwiceheavierthanLily.C:TomisovertwicetheweightofLily.②倍数+形容词比较级+than…③倍数+the(size,height,length,weight,width,depth,age)+of…①倍数（half,once,twice,…times）+as+形容词+asUsethewordsbelowtowritesentencesasintheexamples.Example:temperature/get/lowThetemperaturegetslowerandlower.1.hotmetal/get/bigThehotmetalisgettingbiggerandbigger.2.magnesium/get/hotThemagnesiumisgettinghotterandhotter.3.sun/get/strongduringthemorningThesunisgettingstrongerandstrongerduringthemorning.4.sea/become/warmTheseaisbecomingwarmerandwarmer.A.Underlin