专题02阅读理解之说明文

1.（2023上·河北保定·高二统考期末）Theearthhasmanymysteriesforpeopletoexploreandweliveontheearthforprotection.DoyouknowthattheearthhastwoNorthPoles?There’sthegeographicNorthPole,whichneverchanges.Andthere’sthemagnetic(有磁性的)NorthPole,whichisalwaysonthemove.Overthepast150years,themagneticNorthPolehascasuallywandered685milesacrossnorthernCanada.Butrightnowit’sracing25milesayeartothenorthwest.Thiscouldbeasignthatwe’reabouttoexperiencesomethinghumanshaveneverseenbefore:amagneticpolarflip(翻转).Andwhenthishappens,itcouldaffectmuchmorethanjustyourcompass.

Rightnowonthesurfaceoftheplanet,itlookslikeit’sjustabarmagnet.Ourcompassesarejustpointingtoonepoleatatimebecausethere’smainlyatwo-polesystem.Butsometimes,theearthdoesn’tjusthaveasinglemagneticNorthandSouthPole.Evidencesuggeststhat,forhundredstothousandsofyearsatatime,ourplanethashadfour,six,andeveneightpoles.Thisiswhathashappenedwhenthemagneticpolesflippedinthepast.Andwhenithappensagain,itwon’tbegoodnewsforhumans.

Nowyoumightthink,eightpolesmustbebetterthantwo.Buttherealityisthatmultiplemagneticfieldswouldfighteachother.Thiscouldweakentheearth’sprotectivemagneticfieldbyupto90%duringapolarflip.

Theearth’smagneticfieldiswhatprotectsusfromharmfulspaceradiationwhichcandamagecellsandcausecancer.Withaweakerfieldinplace,somescientiststhinkthiscouldexposeplanestohigherlevelsofradiation,makingflightslesssafe.

Thiscouldalsointerrupttheinternalsenseofdirectioninmanyanimalsthatusethemagneticfieldfornavigation(导航).Evenworse,itcouldmakecertainplacesontheplanettoodangeroustolivein.Butwhatexactlywilltakeplaceonthesurfaceislessclearthanwhatwillundoubtedlyhappeninspace.

Satellitesandspacemissionswillneedext