Air PollutionThere was one thought that air pollution affected only th

AirPollution

Therewasonethoughtthatairpollutionaffectedonlytheareasimmediatelyaroundlargecitieswithfactoriesandheavyautomobiletr affic.____1____

Onseveraloccasionsoverthepastd ecade,aheavycloudofairpollutionhascoveredtheeastoftheUnitedStatesandbroughthealthwarningsinruralareasawayfromanymajorconcentr ationofmanufacturingandautomobiletr affic.Infact,theveryclimateoftheentireearthmaybeinfectedbyairpollution

Somescientistsconsiderthattheincreasingconcentr ationofcarbondioxide((二氧化碳)intheairresultingfromtheburningofcoalandoiliscreatinga"greenhouseeffect".Itconservesheatr eflectedfromtheearthandraisedtheworld’saveragetemperature.___2___ThusmuchofthepolaricecapwillmeltandcitiessuchasNewYork,Boston,Miami,andNewOrleanswillbeinwater.

___3___Thisisaresultthatwouldbeequallydisastr ous.Adropofjustafewdegreescouldcreatesomethingclosebetoanewiceage,andwouldmakeagriculturedifficultorimpossibleinmanyofourtopfarmingareas.

Todaywedonotknowforsurethateitheroftheseconditionswillhappen.___4___Drivenbyeconomicprofit,peopleneglectbythedamageonourenvironmentcausedbythe"advancedcivilization".___5___Butisitr eallyworthwhile?

Perhaps,ifweareluckyenough,thetwotendencieswilloffset(抵消)eachotherandtheworld'stemperaturewillstayaboutthesameasitisnow.

Ifthisviewiscorrect,theworld'stemperatureisraisedonlyafewdegrees.

Maybetheairpollutionisthepricethehumanbeingshavetopayfortheirdevelopment

Atpresent,werealizethatalthoughthesearetheareaswiththeworstairpollution,theproblemisliterallyworldwide

Lately,globalwarmingisbecomingaseriousproblem

Anotherview,lesswidelyheld,isthatincreasingparticularmatterintheatmosphere(大气)isblockingsunlightandloweringtheearth'stemperature.

答案及解析：该空格位于第四段的段首,因此所填句子在结构上必然起着承上启下的衔接作用。纵览全文内容,不难发现选项B中thisview与选项F中的Anotherview信息对应。既然B选硕已经填在了上一段的空格处,那么F选项应该为此处所填句子。