【Howbigisspace?Thatisaquestionmanhasbeenaskingsincethebeginningoftime.Whenyourgrandparentswereinschoolitwas36thattheUniversewasvery37perhapsonly5000lightyears38.500yearsagopeopleconsideredt】

　　Howbigisspace?Thatisaquestionmanhasbeenaskingsincethebeginningoftime.Whenyourgrandparentswereinschoolitwas36thattheUniversewasvery37perhapsonly5000lightyears38.500yearsagopeopleconsideredthattheUniversewasonlyalittlebit39thantheEarth.Inmoderntimeswiththe40oftechnologywearefinallystartingto41theimmense(无边的)sizeoftheUniverseanditismuchbiggerthananyone42haveeverimagined.

　　Scientistscannotstretch(伸展)ameasuringtapefromtheEarthtoanearbystarso43dotheyknowhowfarawaytheyare?Scientistsusesomething44Parallax(视差).Parallaxmeans45thattheylookathowmuchthestarsmoveinthesky46throughouttheyearastheEarthcirclestheSun.Thisisnotsomething47toyou.Infactifyoustretchoutyourhandinfrontofyouand48yourthumbwhile49oneeyeandthentheotheryourthumbwill50tomovebackandforth.Starsdothe51thingbutoureyesaretooclosetoseethe52.HoweverifwetakeapicturewhileononesideofEarth’sorbitandthentakeanotherwhenwegettothe53sideoftheorbitthenwehavealargeenough54thatwecanseethestarsparallaxand55howfarawaytheyreallyare.

　　36.A.measured B.said C.thought D.proved

　　37.A.old B.big C.mysterious D.small

　　38.A.over B.across C.through D.outsides

　　39.A.bigger B.smaller C.heavier D.nearer

　　40.A.popularity B.power C.energy D.strength

　　41.A.grasp B.control C.imagine D.feel

　　42.A.would B.should C.could D.might

　　43.A.what B.why C.how D.when

　　44.A.honored B.called C.considered D.believed

　　45.A.actually B.especially C.generally D.simply

　　46.A.inandout B.backandforth C.soonerorlater D.upanddown

　　47.A.unacceptable B.unfamiliar C.unbelievable D.unnatural

　　48.A.lookat B.shake C.glareat D.notice

　　49.A.covering B.openin