CAn An invEntivE soCiEty gEt BolDEr As it grows olDEr thAt quEstion AFFECts pEoplE oF All AgEs—EspECiAlly thosE living in thE unitED stAtEs,EuropE, AnD jApAn, whiCh ArE ExpECtED to hAvE FEwEr workErs supporting morE rEtirEEs.ACCorDing to sCiEnCE AnDEnginEEring inDiCAtors (sEi):2oo2,issuED By thE nAtionAl sCiEnCEBoArD (nsB、,AmEriCA’s sCiEnCE AnD EnginEEring workForCE will ContinuE to grow in Coming DECADEs, But its AvErAgE AgE is likEly to risE. will sCiEntiFiC workErs in thEir 50s AnD 60s ContinuE to mAkE vAluABlE ContriButions thE rEport AvoiDED Asking whEthEr Aging impAirs CrEAtivity. iF it DoEs, thEn thE growth oF our proDuCtivity AnD improvEmEnt oF our stAnDArD oF living might BE in trouBlE. thErE is AlrEADy A shortAgE oF youngAmEriCAns in rEsEArCh; in 2003 thE ns B、ExprEssED ConCErn ovEr thE unitED stAtEs’ DEpEnDEnCE on ForEign phDs. sCiEntists, oFtEn olDEr onEs, hAvE For yEArs quEstionED how long thEy CAn stAy proDuCtivE. g.h. hArDy sEt thE tonE in his 1940 ClAssiC, A、mAthEmAtiCiAn’sApology. "likE Any othEr mAthEmAtiCiAn who hAs pAssED sixty," hArDy ConFEssED, "i hAvE no longEr thE FrEshnEss oF minD, thE EnErgy, or thE pAtiEnCE to CArry on EFFECtivEly with my propEr jo B、" hE ContinuED thAt "mAthEmAtiCs... is A young mAn’s gAmE." thE AgE lorE oF othEr sCiEnCEs CAn BE similArly mislEADing. thE noBEl lAurEAtE physiCist pAulDirAC hAs suggEstED, tonguE in ChEEk, thAt A physiCist ovEr 30 wAs As gooD As DEAD, AnD thE physiCist-historiAnABrAhAm pAls wrotE oFEinstEin AFtEr 1925 (whEnEinstEin wAs 46)thAt, As FAr As his work wEnt, hE might As wEll hAvE gonE Fishing.AnD yEt thE soCiologist hArriEt zuCkErmAn, in hEr lAnDmArk 1977 Book, sCiEntiFiCElitE ,oBsErvED thAt u.s. noBElists rECEivED thEir prizEs For work DonE whEn thEy wErE, on AvErAgE, nEArly 39. sir nEvill mott won A noBEl prizE in physiCs For his postrEtirEmEnt rEsEArCh. grEAt Biologists sEEm EspECiAlly hArDy. thE gErmAn nAturAlistAlExAnDEr von humBolDt suCCEssFully survEyED hArsh, rEmotE ArEAs oF thE russiAnEmpirE For golDFiElDs AFtEr turning 60,AnD BEgAn puBlishing thE 19th CEntury’s grEAtEst work oF synthEsis,Cosmos, At AgE 76;hE hAD ComplEtED 2000 pAgEs By his DEAth At 89,in 1859. morE rECEntly, hArvArD univErsity’sErnst mAyr wAs still writing pApErs At 100. why, thEn, Do CErtAin rEsEArChErs stAgnAtE whilE othErs Flourish somE might BE intErnAlizing whAt zuCkErmAn CAllED thE "mythology" oF Aging in sCiEnCE.But AnothEr FACtor is thAt Any EDuCAtion hAs Built-in limits.EvEnEinstEin mAy hAvE BEEn Bumping AgAinst thEm. sCiEntists ovEr 40 FACE A ChoiCE: ContinuE using thE EnDowmEnts thAt hAvE sErvED thEm wEll But ArE ChAllEngED By A nEw gEnErAtion, or turn to nEw suBjECts. ACCorDing to thE pAssAgE, sCiEntists ovEr 40 FACE A ChoiCE ______. A、to FACE ChAllEngE By young pEoplE or to rEtirE B、to ContinuE thEir rEsEArCh or to work unDEr nEw suBjECt C.to Exploit thEir EnDowmEnt or turn to nEw suBjECt D.to ACCEpt nEw ChAllEngE From young pEoplE or stAy unproDuCtivE