题目内容：
根据以下材料，回答题Mostpeoplefeellonelysometimes,butitusuallyonlylastsbetweenafewminutesandafewhours.Thiskindoflonelinessisnotserious.Infact,itisquitenormal.Forsomepeople,though,
lonelinesscanlastforyears.Psychologistsarestudyingthisphenomenoninanattempttobetterun-derstandlong-termloneliness.Theseresearchershavealreadyidentifiedthreedifferenttypesoflone-liness.
Thefirstkindoflonelinessistemporary.Thisisthemostcommontype.Itusuallydisappearsquicklyanddoesnotrequireanyspecialattention.Thesecondkind,situationalloneliness,isanatural
result.Forexample,thedeathofalovedone,ormovingtoanewplace.Althoughthiskindoflonelinesscancausephysicalproblems,suchasheadachesandsleeplessness,itusuallydoesnotlast
formorethanayear.Situationallonelinessiseasytounderstandandtopredict.
Thethirdkindoflonelinessisthemostsevere.Unlikethesecondtype,chroniclonelinessusuallylastsmorethantwoyearsandhasnospecificcause.Peoplewhoexperiencehabitualloneli-nesshaveproblemssocializing.Unfortunately,manychronicallylonelypeoplethinkthereislittleornothingtheycandotoimprovetheircondition.
Manyresearchersagreethattheloneliestpeoplearebetweentheages18and25,soagroupofpsychologistsdecidedtostudyagroupofcollegestudents.Theyfoundthatmorethan50%ofthe
studentsweresituationallonelyatthebeginningofthetermasaresultoftheirnewcircumstances,buthadadjustedafterafewmonths.Thirteenpercentwerestilllonelyaftersevenmonthsdueto
shy-nessandfear.Theyfeltveryuncomfortablemeetingstrangers,eventhoughtheyunderstoodthattheirfearwasnotreasonable.Thesituationallonelystudentsovercametheirlonelinessbymaking
newfriends,butthechronicallylonelyremainedunhappybecausetheywereafraidtodoso.
Psychologistsaretryingtofindwaystohelphabituallylonelypeoplefortworeasons.Firstofall,theyareunhappyandunabletosocialize.Secondly,researchershavefoundaconnectionbe-tweenchroniclonelinessandseriousillnesssuchasheartdisease.Whiletemporaryandsituationallonelinesscanbeanormal,healthypartoflife,chroniclonelinesscanbeaverysad,andsome-timesdangerouscondition.
Whatdoesthepassagemainlytalkabout? A．Lonelinessandillnesses
B．Threekindsofloneliness
C．Lonelinessandshyness
D．Threecausesofloneliness
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答案解析：