Weallknowthatitisimpossibleforordinarypeopletomaketheirhomesontheequator(赤道)althoughoftentheymayfeeluncomfortablethere.Millionsdoit.ButasfortheNorthPoleweknowthatitisnotonlyadangerouslycoldpl

　　Weallknowthatitisimpossibleforordinarypeopletomaketheirhomesontheequator(赤道)althoughoftentheymayfeeluncomfortablethere.Millionsdoit.ButasfortheNorthPoleweknowthatitisnotonlyadangerouslycoldplacebutalsothatpeoplelikeyouandmewouldfinditquiteimpossibletolivethere.Atthepresenttimeonlythescientistsandexplorerscandosoandtheyusespecialequipment.Menhavebeentravelingacrossandaroundtheequatoronwheelsontheirfeetorbyshipsforthousandsofyears;butonlyafewmenwithgreatdifficultyandinveryrecenttimehaveevercrossedtheicetotheNorthPole.SoitmaysurpriseyoutolearnthatwhentravelingbyairitisreallysafertoflyovertheNorthPolethanovertheequator.Ofcoursethisisnottrueaboutlandinginthepolarregion(whichpassengeraeroplanesdonotmake)buttheweatherifweareflyingataheightof5000metersabovethePoleisadelight.At4000metersandmoreabovetheearthyoucanalwaysbesurethatyouwillnotseeacloudintheskyasfarastheycanreachinthetropics(热带)ontheotherhandyouarenotcertaintokeepclearofbadweatheratsuchheightsas18000or20000meters.

　　Aeroplanescannotclimbashighorasquicklyincoldairasinwarm.Norcanclouds.Inpracticethisisanadvantagetotheaeroplanewhichisalreadyatagoodheightwhenitreachesthepolarregionandsodoesnotneedtoclimbwhileatthesametimecoldairkeepsthecloudsdown.

　　1.ScientistscanliveintheNorthPolebecause______.

　　A.theyknowtheplacewell

　　B.theyarespeciallytrained

　　C.theyarenotordinarypeople

　　D.theyarewellequipped

　　2.Fromthepassageweknowthatthepolarregionis______.

　　A.agoodplacetoreachbysea

　　B.anattractingplacecoveredbyvariouskindsofplants

　　C.agoodplacetoflyover

　　D.agoodplacetogoonholiday