（2010·广东华南师大附中高三综合测试一）
Judgingfromrecentsurveysmostexpertsinsleepbehaviouragreethatthereisvirtuallyanepidemic（流行病）ofsleepinessinthenation.“Ican’tthinkofasinglestudythathasn’tfoundAmericansgettinglesssleepthantheyoughtto”saysDr.David.Evenpeoplewhothinktheyaresleepingenoughwouldprobablybebetteroffwithmorerest.
Thebeginningofoursleep-deficit（lack）crisescanbetracedbacktotheinventionofthelightbulbacenturyago.Fromdiaryentriesandourpersonalaccountsfromthe18thand19thcenturiessleepscientistshavereachedtheconclusionthattheaveragepersonusedtosleepabout9.5hoursanight.“Thebestsleephabitsoncewereforcedonuswhenwehadnothingtodointheeveningdownonthefarmanditwasdark.”Bythe1950sand1960sthesleepschedulehadbeenreduceddramaticallytobetween7.5and8hoursandmostpeoplehadtowaketoanalarmclock.“Peoplecheatintheirsleepandtheydon’tevenrealizethey’redoingit”saysDr.David.“Theythinkthey’reokeybecausetheycangetbyon6.5hourswhentheyreallyneed7.58orevenmoretofeelideallyenergetic.”
Perhapsthemostmercilessrobberofsleepresearchessayisthecomplexityoftheday.Wheneverpressuresfromworkfamilyfriendsandcommunityincreasemanypeopleconsidersleeptheleastexpensiveitemontheirprogramme.“Inoursocietyyou’reconsidereddynamicifyousayyouneedonly5.5hours’sleep.Ifyou’vegottoget8.5hourspeoplethinkyoulackdriveandambition.”
Todeterminetheconsequencesofsleep-deficitresearchershaveputsubjectsthroughasetofpsychologicalandperformancetestsrequiringthemforinstancetoaddcolumnsofnumbersorrecallapassagereadtothemonlyminutesearlier.“We’vefoundthatifyou’reinsleepdeficitperformancesuffers”saysDr.David.“Short-termmemoryisweakenedasareabilitiestomakedecisionsandtoconcentrate.”
41.Whatisthemaintopicofthepassage?
A.Researchonthecausesandconsequencesofsleep-deficit.
B.Theepidemicofsleepinessinthemoderntimes.
C.Thehistoryofpeople’ssleepingpatterns.
D.Theminimumofoursleepinghours.
42.WhichofthefollowingisDr.David’sopinion?
A.Peoplewhothinktheyare
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