题目内容：
根据以下材料，回答题Youwakeupinthemorning,thedayisbeautifulandtheplansforthedayarewhatyouhavebeenlookingforwardtoforalongtime.Thenthetelephonerings,yousayhello,andthedramastarts.
Thepersonontheotherendhasadepressingtoneinhisvoiceashestartstotellyouhowterriblehismorningisandthatthereisnothingtolookforwardto.Youarestillinawonderfulmood?.
Impossi-ble!
Communicatingwithnegativepeoplecanwashoutyourhappiness.Itmaynotchangewhatyouthink,butcommunicatinglongenoughwiththemwillmakeyoufeeldepressedforamoment'ora
longtime.
Lifebringsupsanddowns,butsomepeoplearestuckinthewrongideathatlifehasnohappi-nesstooffer.Theyonlyfeelgladwhentheymakeothersfeelbad.Nowondertheycanhardlywinothers'pityorrespect.
Whenyoucommunicatewithpositivepeople,yourspiritstayshappyandthereforemorepositivethingsareattracted.Whenthedagger(匕首)ofanegativepersonisputinyou,youfeeltheheavyfeelingthatallinall,bringsyoudown.
Sometimeswehavenochoicebuttocommunicatewithnegativepeople.Thiscould'beaco-worker,orarelative.Inthiscase,saywhatneedstobesaidaslittleaspossible.Sometimesitfeelsgoodtoletoutyourangerbacktothenegativeperson,butallthisdoesistoloweryoutothat
samenegativelevelandtheywon'tfeelashamedofthemselvesaboutthat.
Negativityoftenaffectshappinesswithoutevenbeingrealized.Thenegativewordsofanotheratthestartofthedaycanclingto(附着)youthroughouttherestofyourday,whichmakesyoufeelbadandstealsyourhappiness.Lifeistooshorttofeelnegative.Staypositiveandavoidnegativityasmuchaspossible.
Thepurposeofthefirstparagraphisto__________. A．makeacomparison
B．offeranevidence
C．introduceatopic
D．describeadailyscene
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