判断正误Lighttravelsataspeedwhichisaboutamilliontimes急.

TheSpeedofLight

Lighttravelsataspeedwhichisaboutamilliontimesfasterthanthespeedofsound.

Inonesecond,lighttravelsabout300,000kilometres.

Butsoundtravelsonly0.344kilometres.Youcangetsomeideaofthisdifferencebywatchingthestartofarace.Ifyou

Standsomedistance(距离)awayfromthestarter,youcanseesmokecomefromhisgun

(枪)beforethesoundreachesyourears.

Thisgreatspeedoflightproducessomestrangefacts.Sunlighttakesabout8minutesto

reachus.Ifyoulookatthelightofthemoontonight,rememberthatthelightleftthemoon1.3secondbeforetheyreachedyou.Theneareststarisfarawayfromtheearth.Thelightwhichyoucanseefromittonightstartedtotraveltowardsyoufouryearsagoataspeedofnearly2millionkilometersoneminute.Insomecases(情况)thelightfromoneoftonight’sstartsstartedonitsjourneytoyoubeforeyouwereborn.

Ifwewanttobehonest(诚实),wecannotsay“Thestarsareshiningtonight.”Wehavetosay,“Thestarslookpretty(漂亮).Theywereshiningfouryearsago.Buttheirlighthasonlyjustreachedtheearth..”

判断正误：

（）1.Lightspeedisaboutamilliontimesfasterthansoundspeed.

（）2.Ifyoustand100metresawayfromastarter,youcanhearthegunbeforeyouseethesmoke.

()3.Themoonmustbeabouttwomillionkilometersawayfromtheearth.

()4.Thesunmustbeabout480times300,000kilometresawayfromtheearth..

()5.Themoonlightweseetonightstartedtotraveltowardsusfouryearsago.