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TheMoon,whichhasundergoneadistinctandcomplexgeologicalhistory,presentsastrikingappearance.Themoonmaybedividedintotwomajorterrains:theMaria(darklowlands)andtheTerrace(brighthighlands).Thecontrastinthereflectivity(thecapabilityofreflectinglight)ofthesetwoterrainssuggestedtomanyearlyobserversthatthetwoterrainsmighthavedifferentcompositions,andmissionstotheMoonsuchasSurveyorandApolloconfirmedthissupposition.OneofthemostobviousdifferencesbetweentheterrainsisthesmoothnessoftheMariaincontrasttotheroughnessofthehighlands.Thisroughnessismostlycausedbytheabundanceofcraters:thehighlandsarecompletelycoveredbylargecraters(greaterthan40-50kmindiameter),whilethecratersoftheMariatendtobemuchsmaller.ItisnowknownthatthevastmajorityoftheMoon'scraterswereformedbytheimpactofsolidbodieswiththelunarsurface.MostofthenearsideoftheMoonwasthoroughlymappedandstudiedfromtelescopicpicturesyearsbeforetheageofspaceexploration.Earth-basedtelescopescanresolveobjectsassmallasafewhundredmetersonthelunarsurface.Closeobservationofcraters,combinedwiththewaytheMoondiffuselyreflectssunlight,ledtotheunderstandingthattheMooniscoveredbyasurfacelayer,orregolith,thatoverliesthesolidrockoftheMoon.Telescopicimagespermittedthecatalogingofabewilderingarrayoflandforms.Craterswerestudiedforcluestotheirorigin;thelargewispymarkswereseen.Strange,sinuousfeatureswereobservedintheMaria.Althoughvariouslandformswerecatalogued,themajorityofastronomers'attentionwasfixedoncratersandtheirorigins.Astronomershaveknownforafairlylongtimethattheshapeofcraterschangesastheyincreaseinsize.Smallcraterswithdiametersoflessthan10-15kmhaverelativelysimpleshapes.Theyhaverimcreststhatareelevatedabovethesurroundingterrain,smooth,bowl-shapedinteriors,anddepthsthatareaboutone-sixththeirdiameters.Thecomplexityofshapeincreasesforlargercraters.1.Whatdoesthepassagemainlydiscuss?(A)WhatastronomerslearnedfromtheSurveyorandApollospacemissions.(B)CharacteristicsofthemajorterrainsoftheMoon.(C)TheoriginoftheMoon'scraters.(D)TechniquesusedtocataloguetheMoon'slandforms.2.Thewordundergoneinline1isclosestinmeaningto(A)altered(B)substituted(C)experienced(D)preserved3.Accordingtothepassage,theMariadifferfromtheTerracemainlyintermsof(A)age(B)mannerofcreation(C)size(D)composition4.ThepassagesupportswhichofthefollowingstatementsabouttheSurveyorandApollomissions?(A)TheyconfirmedearliertheoriesabouttheMoon'ssurface.(B)TheyrevealedthatpreviousideasabouttheMoon'scraterswereincorrect.(C)TheywereunabletoprovidedetailedinformationabouttheMoon'ssurface.(D)TheywereunabletoidentifyhowtheMoon'scratersweremade.5.Thewordvastinline11isclosestinmeaningto(A)special(B)known(C)varied(D)great6.AllofthefollowingaretrueoftheMariaEXCEPT:(A)Theyhavesmallcraters.(B)Theyhavebeenanalyzedbyastronomers.(C)Theyhavearoughtexture.(D)Theytendtobedarkerthantheterrace.7.AllofthefollowingtermsaredefinedinthepassageEXCEPT(A)Moon(line1)(B)reflectivity(line3)(C)regolith(line16)(D)Maria(line2)8.Theauthormentionswispymarksinline19asanexampleof(A)anaspectofthelunarsurfacediscoveredthroughlunarmissions(B)acharacteristicoflargecraters(C)adiscoverymadethroughtheuseofEarth-basedtelescopes(D)featuresthatastronomersobservedtobecommontotheEarthandtheMoon9.Accordingtothepassage,lunarresearchershavefocusedmostlyon(A)thepossibilityoffindingwaterontheMoon(B)thelunarregolith(C)catalogingvariouslandformations(D)cratersandtheirorigins10.Thepassageprobablycontinueswithadiscussionof(A)thereasonscratersaredifficulttostudy(B)thedifferentshapessmallcraterscanhave(C)somefeaturesoflargecraters(D)somedifferenceinthewayssmallandlargecraterswereformed