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如图，四棱锥P﹣ABCD中，所有棱长均为2，O是底面正方形ABCD中心，E为PC中点，则直线OE与直线PD所成角为（ ）
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如图所示ABCD是正方形O.是正方形的中心PO⊥底面ABCD底面边长为aE.是PC的中点.1求证PA
如图在四棱锥P.－ABCD中底面ABCD是边长为1的正方形PA⊥底面ABCDPA＝AB点M.在棱PD
在底面是正方形的四棱锥P﹣ABCD中PA⊥底面ABCD点E为棱PB的中点点F在棱AD上平面CEF与
如图所示在四棱锥P.—ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDPD＝DCE.是PC的中点
如图所示在四棱锥P.—ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDPD＝DCE.是PC的中点
如图1在四棱锥P.－ABCD中底面为正方形PC与底面ABCD垂直图2为该四棱锥的主视图和左视图它们是
在四棱锥P.﹣ABCD中PB⊥底面ABCD底面ABCD是边长为2的正方形若直线PC与平面PDB所成的
如图在四棱锥P.―ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDPD=DCE.是PC的中点作E
如图在四棱锥P.﹣ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDE.是PC的中点.1证明PA∥
如图在四棱锥S-ABCD中底面ABCD为正方形侧棱SD⊥底面ABCDE.F.分别是ABSC的中点1求
如图在四棱锥P.﹣ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDPD=DCE.是PC的中点作E
如图所示在四棱锥P.―ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDPD=DCE.是PC的中点
如图已知正方体ABCD－A.1B.1C.1D.1的棱长为2O.为底面正方形ABCD的中心则三棱锥B.
如图在四棱锥P-ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDPD=DCE.是PC的中点作EF
如图在四棱锥P.－ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDPD＝DCE.是PC的中点Ⅰ证
如图所示在四棱锥P—ABCD中底面ABCD是边长为2的正方形侧棱PD⊥底面ABCDPD＝DCE.是P
如图在四棱锥P.—ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDPD=DCE.是PC的中点作E
如图在四棱锥P-ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDPD=DCE.是PC的中点作EF
如图所示在四棱锥P―ABCD中底面ABCD是正方形侧棱PD⊥底面ABCDPD=DCE.是PC的中点.
设四棱锥P﹣ABCD的底面是边长为的正方形侧棱长均为若该棱锥的五个顶点都在球O的球面上则球O的表面积
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FiveyearsagoItookasightseeingtriptoWashingtonDC.Isawmany1nationtreasuresandIalsosawmanypoor2likebeggarsandhomelessfolks.StandingoutsidethemuseumIhearda3behindmeCanyouhelpme?WhenI4aroundIsawanelderlyblindwomanwithherhandsextended伸着.I5intomypockettookoutthe6andplacedtheminherhandwithoutevenlooking7her.IhatedbeingtroubledbyabeggarwhenIwas8seeingpeopleandthingsaround.Buttomy9theblindwomansmiledandsaidIdon'tneedyourmoney.Ijustneedyour10tofindthepostoffice.IsoonrealizedIhad11anotherpersonforwhatIthoughtshehadtobe. Thisexperiencemademefeelbadaboutmyself.12inmyownlifeIhavealso13manyactsofprejudice偏见.WhenIworkedasabusboyattheageof17Iheardafathertellhissonthathewould14likemeifhedidn'tworkharder.Ishouldhave15thetreatmentandknownwhatitislike.Butnowlivingagoodlifeasanetworkengineerit'stooeasytoforgetmy16toforgetwhoIamandwhereIhavebeenandtoignore17Iwanttogo.Theblindwomancuredmeofmy18.ShemademerealizethatIshouldalwaysstayhumble谦卑的andkeepmyeyesandheart19 BythewayIhelpedthatladytogettothepostoffice.I20hopetothankherforthepricelesslessonshegaveme. 1A.wonderful B.official C.colorful D.popular 2A.workers B.audience C.people D.students 3A.cry B.voice C.shout D.noise 4A.ran B.walked C.looked D.turned 5A.reached B.felt C.checked D.stepped 6A.papers B.pictures C.coins D.cards 7A.for B.at C.after D.through 8A.imagining B.finishing C.practicing D.enjoying 9A.surprise B.pleasure C.interest D.sorrow 10A.hand B.idea C.help D.suggestion 11A.trusted B.judged C.forgot D.met 12A.Inshort B.Inbrief C.Inorder D.Infact 13A.experienced B.watched C.found D.accepted 14A.givein B.falldown C.endup D.passaway 15A.kept B.remembered C.received D.refused 16A.pain B.joy C.future D.past 17A.where B.why C.when D.how 18A.foolishness B.kindness C.blindness D.illness 19A.calm B.open C.warm D.shut 20A.equally B.gradually C.frequently D.sincerely
Badnewssells.Ifitbleedsitleads.Nonewsisgoodnewsandgoodnewsisnonews.Thosearetheclassicrulesfortheeveningbroadcastsandthemorningpapers.Butnowthatinformationisbeingspreadandmonitored监控indifferentwaysresearchersarediscoveringnewrules.Bytrackingpeople'se﹣mailsandonlinepostsscientistshavefoundthatgoodnewscanspreadfasterandfartherthandisastersandsobstories. The‘ifitbleeds'ruleworksformassmediasaysJonahBergerascholarattheUniversityofPennsylvania.Theywantyoureyeballsanddon'tcarehowyou'refeeling.Butwhenyoushareastorywithyourfriendsyoucarealotmorehowtheyreact.Youdon'twantthemtothinkofyouasaDebbieDowner. Researchersanalyzingword﹣of﹣mouthcommunication﹣e﹣mailsWebpostsandreviewsface﹣to﹣faceconversations﹣foundthatittendedtobemorepositivethannegative消极的butthatdidn'tnecessarilymeanpeoplepreferredpositivenews.Waspositivenewssharedmoreoftensimplybecausepeopleexperiencedmoregoodthingsthanbadthings?TotestforthatpossibilityDr.Bergerlookedathowpeoplespreadaparticularsetofnewsstories:thousandsofarticlesonTheNewYorkTimes'website.HeandaPenncolleagueanalyzedthemoste﹣mailedlistforsixmonths.Oneofhisfirstfindingswasthatarticlesinthesciencesectionweremuchmorelikelytomakethelistthannon﹣sciencearticles.HefoundthatscienceamazedTimes'readersandmadethemwanttosharethispositivefeelingwithothers. Readersalsotendedtosharearticlesthatwereexcitingorfunnyorthatinspirednegativefeelingslikeangeroranxietybutnotarticlesthatleftthemmerelysad.Theyneededtobearoused激发onewayortheotherandtheypreferredgoodnewstobad.ThemorepositiveanarticlethemorelikelyitwastobesharedasDr.BergerexplainsinhisnewbookContagious:WhyThingsCatchOn. 8.Whatdotheclassicrulesmentionedinthetextapplyto? A.Newsreports. B.Researchpapers. C.Privatee﹣mails. D.Dailyconversations. 9.WhatcanweinferaboutpeoplelikeDebbieDowner? A.They'resociallyinactive. B.They'regoodattellingstories. C.They'reinconsiderateofothers. D.They'recarefulwiththeirwords. 10.Whichtendedtobethemoste﹣mailedaccordingtoDr.Berger'sresearch? A.Sportsnews. B.Sciencearticles. C.Personalaccounts. D.Financialreviews. 11.Whatcanbeasuitabletitleforthetext? A.SadStoriesTravelFarandWide B.OnlineNewsAttractsMorePeople C.ReadingHabitsChangewiththeTimes D.GoodNewsBeatsBadonSocialNetworks.
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