Overeightmonthsthescientiststested20drugs,allwithnegativeresults.Finallytheytestedtheanticonvulsantd rugethosuzimide.Researchersfoundthatthedrugextendedthelifespanofroundwormsfrom16.7daysto19.6days,a17percentincrease。
A.ButKomfeldsaidscientistswillnotknowabouttheapplicabilityofthedrugsinhumansuntilasimilarstudyisdoneonhumans.“What’sveryencouragingisthatthesedrugsweredevelopedtotr eathumans,andtheyarewellunderstood,becausethey’vebeenusedforalongtime,”hesaid。
B.Laterthescientistsdiscoveredthattworelatedanticonvulsantd rugsalsolengthenedthelivesoftheworms-inthecaseofonedrug,byalmost50percent.“Thiswasabigsurprisetouse,Komfeldsaid.”“Wedidn’tthinkanticonvulsantd rugshadanyparticularrelationshiptoaging.Thatconnectionwascompletelyunexpected.”
C.Roundwormsareapoorsubjectforexperiments,becausetheyarenotlikehumans,eventhoughtheirmoleculesaresimilar.Forexample,theyhavenobones,nordotheyshowemotions,makingitd ifficulttoknowhowexactlyhumansubjectswouldreacttothesedrugsinlargequantities.However,usingthewormsallowsexperimentstobeconductedquickly,becausetheydonotliveforlong。
D.“Somehowtheneuralactivityseemstoregulatetheagingofallofthebodytheskin,musculature,andreproductivetr act,”Kornfeldsaid.“Somehowthenervoussystemcoordinatestheprogressofallthesetissues,evidently,thoughthelifestages.Butwedon’tknowhowitd oesthat.”
E.Thediscoverymayalsoshedlightonthelittle-understoodagingprocess.Sincethedrugsactontheneuromuscularsystemsofbothhumansandworms,thefindingshintatalinkbetweenneuralactivityandaging。
F.Unlikevertebrates,thewormsareidealsubjectsforthestudyofagingbecauseoftheirshortlifespans,whichlastonlyacoupleofweeksinalaboratory.Thewormiswellknowningenetics,andtheworm’sgenomehasbeensequenced。
G.Useofthisdrughasbeenpermittedbylawsince1998andwideruseisnowexpectedasaresultofthestudies.“Wecanclearlylinkthisdrugwithhumanaging,butwestillneedtofindproof,saysKornfeldoptimistically.”
正确答案：F空前文字概括介绍了Evason的实验，只有选项F非常清楚地描述了实验对象，并说明为什么使用这个实验对象的原因。这实际上都是介绍实验的一部分。
