【Haveyoueverheardthesaying“AllroadsleadtoRome”?Atonetime,thiswasprettymuchtrue.DuringtheRomanEmpire,lotsofroadswerebuiltinordertomovearmies,sendmessagesbycourier(信使),andmaketradeeasier.Thisconstructio】

　　Haveyoueverheardthesaying“AllroadsleadtoRome”?Atonetime,thiswasprettymuchtrue.DuringtheRomanEmpire,lotsofroadswerebuiltinordertomovearmies,sendmessagesbycourier(信使),andmaketradeeasier.Thisconstructionworkwentonforfivecenturies!IfalltheroadsbuiltduringtheRomanEmpirewereputtogetherendtoend,theywouldcircletheequatortwice.

　　ThenetworkofRomanroadswasbegunin312BC.Itwasdemandedthattheroadsbebuiltstrongsothattheywouldnotfalldown.Romansoldiers,supervised(监督)byengineers,laiddowntheroadsinaspecialpatternoflayers.Thefirstlayerwasmadeofsand.Next,thebuildersaddedrocksandrubble.Ontopofthesematerialscamegravel.Onthissolidfoundation,theroadbuildersplacedpavingstones.

　　Also,Romanroadswerecambered.Thismeansthattheywerebuilthigherinthemiddlethanontheedges,allowingrainwatertorunoff,whichpreventedflooding.Weusethesametechniqueinbuildingroadstoday.TheRomansalsolaidoutroadsoverhillswhennecessary,settingthemdowninazigzagpatterntomaketheroadrisegradually.

　　AllRomanroadshadmilestones(里程碑),placedeverythousandspaces(aRomanmile).Themilestonestoldwhentheroadwasbuilt,whowasemperoratthetime,theroad’sdestination,howfarthetravelerwasfromthedestination,andhowmanymileshadbeentraveledsincethebeginningoftheroad.Thisinformationwasagreathelptotravelers.

　　Becauseoftheirexcellenceinconstruction,itreallyisnosurprisethatmanypartsofRomanroadstillexisttoday.TheseroadwaysareoneofthemostimpressiveaccomplishmentsoftheRomanEmpireWhatdoestheunderlinedsentenceinthefirstparagraphmean?WhichofthefollowingcorrectlyshowsthestructureoftheRomanroads?Whatinformationcanyoufindonthemilestones?Thepassagemainly______

　　A.TheRomanEmpirewasverypowerful

　　B.LotsofroadswerebuiltduringtheRomanEmpire

　　C.TheroadsbuiltduringtheRomanEmpirewereverylong

　　D.TheroadsbuiltduringtheRomanEmpirewereveryconvenient

　　A.Pavingstones

　　Gravel

　　Rocks&rubble

　　Sand

　　B.Gravel

　　Rocks&rubble

　　Sand

　　C.Sand

　　Rocks&a