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2017成人高考专升本英语真题
一、阅读理解
Ifyoulookatthenightsky,you’lloftenseestarsmoving
veryquickly.Infact,theymovemuchmorequicklythantheyshould
accordingtotheirsizeandthelawsofphysics.
Scientistsdonotcompletelyunderstandwhythespeedofthese
starsissohigh.Butmanybelievethereasonisthatmuchofthe
universeismadeofsomethingcalled“darkmatter”.Groupsofstars
calledgalaxies,suchastheMilkyWay,mightevenbemadeupof90
percentdarkmatter.
Howmuchsomethingweighsdependsonwhereitis.Thesame
objectweighsonlyhalfasmuchonMarsasitdoesonEarthandalmost
threetimesasmuchonJupiter.Soscientistsprefertotalkaboutthe
mass(质量)ofsomethingratherthanhowmuchitweighs,becausemass
doesnotchange.Theycanworkoutthemassofgalaxiesbymeasuringthe
distancebetweenthemandthespeedtheymoveat.
Recently,JorgePeñarrubia,asenioracademicatEdinburgh
University,UK,andhisteamdiscoveredsomethinginteresting:Themass
oftheMilkyWayisonlyhalfasmuchasthemassofanothernearby
galaxy,Andromeda.Thisseemsstrange,anddarkmattermayexplainwhy.
Findingoutmoreaboutdarkmattercouldhelpusunderstandhow
theuniversebegan,butthisisnoteasy.Lotsofscientistswith
differenttypesofexpertknowledgeareworkingontheproblem.
Wecan’tseedarkmatter,it’sverydifficulttomeasureand
wecan’tfindoutitsmass.Unlikestars,darkmatterdoesn’tproduce
orreflectlight.Butwecanmakeagoodguessthatitistherebecause
ofthewaythingsmoveandthewaylightbends.Expertsnowthinkdark
mattermaybeverydifferentfromthematterthatwefindonEarth.
Theremayalsobefivetimesasmuchdarkmatterintheuniverseas
ordinarymatter.
1.Somethingthatweighs15kgonEarthweighsabout_____on
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