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1、2019-2020年高二英语上学期第十八周周练试题无答案一．阅读理解Eveniftreescannotwalk,theyarestillonthemove.InpartsoftheArctic,entireforestsaremovingnorthward.AcrosstheArctic,temperaturesarerisingfasterthananywhereelseintheworld.Asthathappens,thetreelinethatmarkswhereforestsstopandthetreelesstundra(
2、冻原)startshasbeenshiftingnorthward.Treesgrowingalongthetreelinemustprotectthemselvesfromthecoldwind.Todothis,plantstendtogrowhorizontal(水平的)brancheslowtotheground.Theenergyittakesfortreestogrowthiswaymeanstheydon'thaveenoughenergytomakeseeds.ButasEarth'sclimatehasbeenwar
3、ming,treesnolongerhavetojustgrowhorizontally.Manycaninsteadgrowuptowardthesky.Thistakeslessenergy.Andwithallthatleftoverenergy,thesetreeshavestartedproducingmoreseeds.Thishappensespeciallyinplaceswherewhitespruce(白云杉)grows.Whitespruce,whichisaNorthAmericantree,isquiteab
4、letoproducealotofseeds,whichcanmovelongdistancesinthewind.Whenwindblownseedsenduponthetundrabeyondthetreeline,theyeventuallycansprout(发芽)newtrees.Thisexplainshowaforestcanmove.Ofcourse,theprocesswouldworkonlyifthetundrawerewarmenough.Butinrecentyears,thewholeplanethasbe
5、enwarming.Newtreeswillprovidesheltersforsomesnow.Keepingthesun'sraysfrommakingthewhitesurfacedisappear.Instead,thetreesabsorbthesun'sheat.Thiswarmsthesurroundingair.Theextrawarmthencouragesevenmoretreestoproduceseeds.Thatfurtherboostsaforest'sabilitytoexpand.Inaddition,
6、moretreeswilltrapmoresnow,preventingmuchofitfrombeingblownaway.Snowcantrapheatinthesoilbelow,whichencouragestreestogrow.Therecentriseoftemperatureshashelpedmoretreesgrowpastthetreeline.Peopleworryaboutimpactsontheanimalsthatdependonfrozenconditionsforfoodandshelter.32．W
7、hatisthemaincauseofthetreesintheArcticmovingnorthward?A．Theshrinkingofnortherntundra.B．Therisingtemperature.C．Thefierceandcoldwind.D．Theabundantresourcesinthenorth.33．Whatdoestheunderlinedword“this”inParagraph2mean?A．Toproducemoreseeds.B．Tomovenorthward.C．Torespondtothe
8、climatechange.D．Toprotectthemselvesfromthecoldwind.34．Whatcanbeinferredfromthelastparagraph?A．Newtreescantrapt
