题目内容：
根据以下材料，回答题
MiddleAge:aLowPointforMost
Peoplearoundtheglobehittheheightoftheirmiseryanddepressioninmiddle（1）,anewntemationalstudysuggests.ThefindingbyBritishandAmericanresearcherswasbasedonananalysisofwell-beingamongapproximately2millionpeoplein80nations.Withfewexceptions,theobservationappearstoapplyacrosstheboard,regardless（2）gender(性别),culture,geography,wealth,jobhistory,education,andmarriageorparentalstatus.
"Thescientificfactseemstobethathappinessandpositivementalhealthfollowagiant'U'（3）throughlife,"saidstudyauthorAndrewJ.Oswald,aprofessorofeconomicsatWarwickUniversityinWarwickshire,England."Fortheaverageperson,it'shighwhenyou're20,andthenitslowly（4）andbottomsoutinyour40s.Butthegoodnewsisthatyour（5）healthpicksupagain,andeventuallygetsbacktothehighlevelsofyouryouth."
Thefindingwas（6）onthepoolingofseveraldifferentsourcesofhappinessdata,including:twomulti-decadehappiness/satisfactionsurveys(firstlaunchedinthe1970s),involvingabout500,000AmericanandWesternEuropeanmenandwomen;fourroundsofthe80-nation"WorldValuesSurvey"（7）between1981and2004inNorthAmerica,EasternandWesternEurope,Asia,Africa,Australia,andCentralandSouthAmerica;anda2004-2007survey（8）nearly1millionBritons.
Thebottom-line:Formostpeoplethroughouttheworld,thehighestprobabilityfor（9）strikingisaround44yearsofage.
IntheUnitedStates,however,someas-yetunexplained（10）differenceswereobserved,
withhappinessamongmendippingthemostintheirearly50s,whereaswomenhittheirnadir(最低点)aroundtheageof40.
Theresearcherscautionedthatcheerfulpeopletendtolivelongerthanunhappy（11）–afactthatmighthaveskewed(使偏斜)theoverallfinding.Buttheyalsosuggestedthatevidenceofahappiness（12）mightsimplyreflectamidlifechoicetogiveuplong-heldbutnolongertenable(守得住的)aspiration(志向),followedbyasenior'ssenseofgratitudeforhavingsuccessfullyendured（13）othersdidnot.
"Thatsaid,somemightfredithelpfulsimplytounderstandthegeneral（14）ofmentalhealthastheygothroughtheirownlife,"saidOswald."Itmightbeusefulforpeopletorealizethatiftheyare（15）intheir40sthisisnormal.Itisnotexceptional.Andjustknowingthismighthelp."
回答(1)题 A．age
B．place
C．height
D．degree
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