2017年12月英语六级阅读练习:段落匹配题（三）思维导图

ThedifferencebetweenaliquidandagasisobviousundertheconditionsoftemperatureandpressurecommonlyfoundatthesurfaceoftheEarth.Aliquidcanbekeptinanopencontainerandfillittothelevelofafreesurface.Agasformsnofreesurfacebuttendstodiffusethroughoutthe11available;itmustthereforebekeptinaclosedcontainerorheldbyagravitationalfield,asinthe12ofaplanet'satmosphere.Thedistinctionwasa13featureofearlytheoriesdescribingthephasesofmatter.Inthenineteenthcentury,forexample,onetheorymaintainedthataliquidcouldbe"dissolved"inavaporwithoutlosingitsidentity,andanothertheory14thatthetwophasesaremadeupofdifferentkindsofmolecules.Thetheoriesnowprevailingtakeaquitedifferentapproachbyemphasizingwhatliquidsandgaseshavein15Theyarebothformsofmatterthathaveno16structure,andtheybothflowreadily.

Thefundamentalsimilarityofliquidsandgasesbecomesclearlyapparentwhenthetemperatureandpressureare17somewhat.Supposeaclosedcontainer18filledwithaliquidisheated.Theliquidexpands,orinotherwordsbecomeslessdense;someofitevaporates.Incontrast,thevaporabovetheliquidsurfacebecomesdenserastheevaporatedmoleculesare19toit.Thecombinationoftemperatureandpressureatwhichthedensitiesbecome20iscalledthecriticalpoint.

A.added

B.case

C.prominent

D.held

E.equal

F.partially

G.example

H.previous

I.space

J,lifted

K.permanent

L.particularly

M.extended

N.raised

0.common

11.I12.B13.C14.D15.O16.K17.N18.F19.A20.E