【请大神指教这篇英语阅读理解答案是什么?Mostoftheworld’sdiamondscomefromAfrica,butthereisoneplaceintheUnitedStateswheretheyarefounds.ItisnearMurfreesboro,Arkansas.DiamondswerefirstfoundnearMurfreesboroin1】

　　请大神指教这篇英语阅读理解答案是什么?

　　Mostoftheworld’sdiamondscomefromAfrica,butthereisoneplaceintheUnitedStateswheretheyarefounds.ItisnearMurfreesboro,Arkansas.

　　DiamondswerefirstfoundnearMurfreesboroin1906.About50thousandshavecomefromthisfield.One40carat(克拉)diamondwasthelargesteverfoundinNorthAmerica.Butmostofthestonesweretoosmalltomakeminingworthwhile.Soonallminingstoppedthere.TodayavisitortoMurfreesborohuntfordiamondhimself.

　　Afewdiamondshavebeenfoundinsandandgravel(砾石)alongtheGreatLake,too.Thisisnotwheretheywereoriginallyfound.Theymayhavebeenformedfartothenorthandcarriedsouthbythelastgreatglaciers(冰川).

　　46.Mostdiamondshavebeenfoundin____.

　　A.NorthAmericaB.SouthAmericaC.AfricaD.Arkansas

　　47.Diamondsintheiroriginalgroundhavebeenfound_____.

　　A.inArkansasB.inseveralstatesC.aroundtheGreatLakeD.Alloftheabove

　　48.TheMurfreesborofieldwas____.

　　A.neverminedB.mineduntiltherewerenomorediamonds

　　C.notworthminingD.minedlargevaluablestones

　　49.InMurfreesborotoday,thevisitorscan____.

　　A.watchminersatworkB.exploreanoldmineC.huntfordiamondsD.findlargevaluablestone

　　50.ThediamondsfoundalongtheGreatLakeswere____.

　　A.carriedtherefromotherplacesB.notfoundintheiroriginalground

　　C.foundintherockswheretheywereformedD.bothAandB