河北省武邑中学高二上学期英语课堂练习55.doc

EnjoyYourself2AItiseasiertofloatintheoceanthanitistofloatinaswimmingpool.Doyouknowwhy?Oceanwaterisfullofsalt--andsaltwatercanholdupmoreweightthanfreshwater.Seeforyourself!YouwillNeed:3cupsofwarmwaterMeasuringcup(量杯)Wide-mouthedjarSaltSpoonRaw(生的)potatoYouWillDo:1.Pour1.5cupsofwarmwaterintothejar.2.Add1/3cupofsalt.3.Stir(搅拌)untilthesaltiscompletelydissolved.4.Addanother1.5cupsofwater.Pouritslowlyoverthebackofthespoonintothejarsothatthetwoliquidswillnotmixtogether.5.Gentlyplacethepotatointothejar.Donotdropit.WhatWillHappen:Thepotatowillsink--butonlyhalfway!Why?Saltwaterisheavierthanfreshwatersoitwillstayonthebottom.Thefreshwaterwillremainontop.Thepotatoisheavierthanthefreshwaterbutitislighterthanthesaltwater.Thatiswhythepotatowillsinkhalfwaydown.1.Intheexperimentwhatshouldyoudorightafteryoupourthewateroverthespoon?A.Addthesalttothewater.B.Stirthesaltintothewater.C.Placethepotatointhejar.D.Pourwarmwaterintothejar.2.InStep4oftheexperimentwhydoyoupourthewateroverthespoon“slowly”?A.Itiseasiertoseewhatyouaredoing.B.Itpushesthefreshwatertothebottom.C.Itwillkeepthewaterfromcomingout.D.Itwillkeeptheliquidsfrommixingtogether.3.Inwhichstepoftheexperimentdoyouaddthesalt?A.Step1B.Step2C.Step3D.Step4【答案】1.C2.D3.B【解析】本文介绍了一个证明盐水的浮力比淡水的浮力大的实验。1.C细节理解题。根据YouWillDo:中的5Gentlyplacethepotatointothejar.Donotdropit.可知在实验中当你把水倒在勺子上后你应该把土豆放入坛子中。故选C.2.D细节理解题。根据Addanother1.5cupsofwater.Pouritslowlyoverthebackofthespoonintothejarsothatthetwoliquidwillnotmixtogether中的sothatthetwoliquidwillnotmixtogether指这两种液体不要混在一起。故选D.3.B细节理解题。根据YouWillDo:中的2Add1/3cupofsalt.可知要在第2步时加盐。故选B。BWriterLiufang’sfirstnovelaboutthelifeofatea