【ThePepperedMothakindofinsectisfoundinEngland.Itislightbrownincolorandlikestosettleontreeswhicharealsolightbrown.Thismakesthemothdifficulttobeseenandbirdsarelesslikelytonoticeandeatit.】

　　ThePepperedMothakindofinsectisfoundinEngland.Itislightbrownincolorandlikestosettleontreeswhicharealsolightbrown.Thismakesthemothdifficulttobeseenandbirdsarelesslikelytonoticeandeatit.

　　Butwiththedevelopmentofindustrysmokefromfactoriesbegantoreachthetreeswherethemothsettled.Itmadethetreesblacker.Thensomethingverystrangetookplace:inindustrialareasthePepperedMothbegantochangecolor.Itbecamedarkeraswell.Althoughthechangetookseveralyearssomescientistssoonnoticedthatnewly-bornmothswerealittledarkerthanusual.

　　AscientistcalledKettleWelldecidedtomakeacarefulstudyofthis.HemarkedsomeofthelightmothsandsomeofthedarkeronesandsetthemfreeinthewoodsnearBirminghamanindustrialcity.Laterheretargetasmanythemarkedmothsaspossible(Theresultwasgiveninthechart).

　　KettleWell’sresearchwasdoneintheearly1950s.SoonafterwardsBritainintroducednewlawstoreducesmokeandfactorypollution.

　　CanyouimaginewhatwouldhappentothePepperedMothastheairbecamecleaneragain?

　　lightmoths

　　darkermoths

　　Mothssetfree

　　201

　　601

　　Mothsrecaught

　　34(16%)

　　206(34%)

　　1.ThetreeswherethePepperedMothsettledchangedtheircolorbecause_____________________________.

　　A.thePepperedMothchangeditscolor

　　B.thePepperedMothcouldn’tbeeasilyfoundonthem

　　C.industryinEnglanddevelopedquickly

　　D.thesmokefromfactoriespollutedthem

　　2.ThePepperedMothbegantochangeitscolorinindustrialareasbecause _____________________________.

　　A.itchangeditscolorallthetime

　　B.itwasfondofthecolorofitslivingplace

　　C.ithadtoprotectitselfbydoingso

　　D.itwasaspecialsortofinsect

　　3.FromtheresultsofKettleWell’sresearchwecanseethat_________________.

　　A.manymoreofthelightmothswerekilledoreaten

　　B.morethanone-fifthofthelightmothsescapedbeingkilled

　　C.threetimesasmanydarkmothswerekeptsafeaslightone