英语六级阅读理解考试题模拟练习2017年英语六级阅读理解考试题模拟练习旧书不厌百回读，熟读精思子自知。以下是小编为大家搜索整理的2017年英语六级阅读理解考试题模拟练习，希望能给大家带来帮助!更多精彩内容请及时关注我们应届毕业生考试网!ThedifferencebetweenaliquidandagasisobviousundertheconditionsoftemperatureandpressurecommonlyfoundatthesurfaceoftheEarth.Aliquidcanbekeptinanopencontainerandfillittothelevelofafreesurface.Agasformsnofreesurfacebuttendstodiffusethroughoutthe11available;itmustthereforebekeptinaclosedcontainerorheldbyagravitationalfield,asinthe12ofaplanet'satmosphere.Thedistinctionwasa13featureofearlytheoriesdescribingthephasesofmatter.Inthenineteenthcentury,forexample,onetheorymaintainedthataliquidcouldbe"dissolved"inavaporwithoutlosingitsidentity,andanothertheory14thatthetwophasesaremadeupofdifferentkindsofmolecules.Thetheoriesnowprevailingtakeaquitedifferentapproachbyemphasizingwhatliquidsandgaseshavein15Theyarebothformsofmatterthathaveno16structure,andtheybothflowreadily.Thefundamentalsimilarityofliquidsandgasesbecomesclearlyapparentwhenthetemperatureandpressureare17somewhat.Supposeaclosedcontainer18filledwithaliquidisheated.Theliquidexpands,orinotherwordsbecomeslessdense;someofitevaporates.Incontrast,thevaporabovetheliquidsurfacebecomesdenserastheevaporatedmoleculesare19toit.Thecombinationoftemperatureandpressureatwhichthedensitiesbecome20iscalledthecriticalpoint.A.addedB.caseC.prominentD.heldE.equalF.partiallyG.exampleH.previousI.spaceJ,liftedK.permanentL.particularlyM.extendedN.raised0.common参考答案II.I12.B13.C14.D15.O16.K17.N18.F19.A20.E