选择题解析ProbablyyouhaveseenphotographsoftheGrandCanyon(峡谷),thegreatvalleyinthedesertcountryofArizona.Butyoumustgothereyourselftofeelitstruesizeandbeauty.TheGrandCanyonisoneofthegreatestnaturalwondersoftheworld.
TheColoradoRiverformedtheGrandCanyonovermillionsofyears.Slowly,therivercutdownthroughhardrock.Atthesametime,thelandwasrising.Today,thecanyonisoneandahalfkilometresdeepand445kilometreslong.Theoldestrocksatthebottomofthecanyonaremorethan1billionyearsold.Thewidthvariesfromabout200metresto29kilometresacross.Therim(边缘)ortopofthecanyonisabout2,300metesabovesealevelontheSouthRim,andabout3,000metresontheotherside,theNorthRim.Asaresult,therearedifferentkindsofplantsandanimalsonoppositesidesofthecanyon.TheSouthRimisadrydesertcountry.TheNorthRimhastallforests.
Thecanyonlooksdifferentatdifferenttimesofday,andindifferentseasonsandweather.Atsunriseandsun-setthered,gold,brown,andorangecoloursoftherocksareespeciallyclearandbright.Inwinter,thecanyonispartlycoveredwithsnow.
TheviewfromtheSouthRimoftheGrandCanyonisthebest.MostvisitorscometotheSouthRimandstayincampgroundsorhotels.Everypointalongthecanyon'sedgeoffersadifferentview.
TheNorthRimoftheCanyonisquieter.IttakesalldaytodrivetherefromtheSouthRimbecausethereisonlyonebridgeacrosstheColoradoRiver.Ontheway,yougothroughNavadoIndianlands,andacolorfulpinkdesertcalled"ThePaintedDesert".
YoucanwalkdownintotheGrandCanyon,oryoucangodownonthebackofamule(小型电动机车).YoucanalsotakeaboattripdowntheColoradoRiver,andcamponthebeachesatnight.ButwhetheryouseetheGrandCanyonfromthetoporthebottom,itwillbeanexperiencethatyouwillneverforget.
88.ThesealevelonbothsidesoftheGrandCanyonis____.
A.thesameB.changingwithtimeC.variousD.verylow
90Ifyougotovisitthecanyonyou'dbettergoto____.
A.theSouthRimB.theNorthRimC.thebottomD.thetopofatree
KEY:ca
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