第三部分：阅读理解（共20小题；每小题2分，满分40分）

Mostchildreneventheyoungestofchildrenaredelightedtobearoundcatsanddogs.Butthesepetscarryplentyofgermsandallergens(过敏原)promptingresearcherstoask:Arecatsanddogsreallysafeforchildren?

Astudyfindsthatcontrarytomanyparents’fearsowningcatsordogsdoesnotincreaseachild’sriskofdevelopingallergiesandinfactmayactuallyprotectthem.Thestudy’sleadauthorDr.DennisOwnbyoftheMedicalCollegeofGeorgiasaidthatevenhewas“verysurprised”bytheresults.Ownbyandcolleaguesfollowedmorethan470childrenfrombirthtoage6or7comparingthoseexposedtocatsanddogsduringtheirfirstyearsoflifetothosewhowerenot.

Byusingskin-pricktestsfordetectingcommonallergiestheresearchersfoundthatcontrarytowhatmanydoctorshadbeentaughtforyearschildrenwhohadlivedwithapetwerenotatgreaterrisk.

Evenmoreremarkablechildrenwhohadtwoormoredogsorcatshadanevengreaterreductionupto77percentinriskofallergies.Researcherssuggestthisprotectiveeffectmaybetheresultofearlyexposuretolotsofbacteriathatarecarriedbydogsandcats.Exposingyoungchildrentothesebacteriahelps“exercise”theirimmune（免疫的）systemsearlyinlifesothatthey’rebetterabletoresistallergicdiseaseslater.

“There’ssomethingveryimportantinthefirstyearsoflifewhentheimmunesystemisdevelopingthatwecanretrainitawayfromanallergicresponse”saidDr.WilliamDavis.

Andwhileresearchersarenotencouragingparentstobuydogsorcatsjusttoreduceachild’sallergyrisktheysayifafamilyalreadyhasoneormoreanimalsthere’snoneedtogetridofthem.

56．Whydotheresearchersfeel“verysurprised”bytheresultsofthestudy?

A.Becausetheresultsarecontrarytowhattheyhaveexpected.

B.Becausesomanyfamiliesaregoingtogetridoftheircatsanddogs.

C.Becauseparentsaresomuchworriedabouttheirchildren.

D.Becausechildrenwithanimalsmaydevelopallergieseasily.

57．Comparedwithchildrenwhohavepetsthosewhohaven’t________.

A.willlosethechancetodevelopimmunesystem

B.maysufferallergicdiseasesmoreoften

C.willre