第三部分:语法填空(共两节,满分20分,每小题1分)根据文段内容或提示,填写正确的单词,每空只能填写一个单词。Nooneknowsexactly__31___theearthbegan,asithappenedsolongago.However,accordingtoa__32___(wide)acceptedtheory,theuniversebegan___33___a“BigBang”thatthrewmatterinalldirections…..Whatitwastobecomewas__34___(certain)untilbetween4.5and3.8billionyearsago__35___thedustsettledintoasolidglobe.Theearthbecamesoviolent__36___itwasnotclearwhethertheshapewouldlastornot…….Peopleare__37__(put)toomuchcarbondioxideintotheatmosphere,whichpreventsheatfrom__38____(escape)fromtheearthintospace.Asaresultofthis,manyscientistsbelievetheearthmaybecometoohottoliveon.So__39____lifewillcontinueontheearthformillionsofyearstocomewilldependonwhetherthisproblemcanbe__40___(solve).