搜题
某校有高一学生400人，高二学生302人，高三学生250人，现在按年级分层抽样，从所有学生中抽取一个容量为190人的样本，则应该在高_____学生中，剔除_____人，高一、高二、高三抽取的人数依次是____．
求下列函数的一阶微分：(1)y=πe+ex+xπ(2)y=πeexxπ(3)y=√x(1+cos2x)(4)x3+y3-3axy=0(α>0，是常数)
设y=xey，则dy=()
A.[ey/(xey-1)]dx
B.[ey/(1-xey)]dx
C.[(1-xey)/ey]dx
D.[(xey-1)/ey]dx
WelcometoNorthRoadMedicalCentre!Weareopenfrom8:30a.m.until6p.m.MondaytoFriday.Appointments（预约）withthedoctorsandnursesareacceptablebothmorningandafternoon.However,asame-dayappointmentmaynotnecessarilybewithyourusualdoctor.Patientsmaybeseenbyanymemberoftheteam.Ifyoudecidetoregister（注册）withus,pleasespeaktooneofourreceptionists（接诊员）Youwillneedtocompletearegistrationform.Eachnewpatientisaskedtoanswersomemedicalquestions.Youshouldalsomakeanappointmenttoseeoneofthenursesforahealthchecksoonafterregistering.Thereissometimesadelayinhandingovermedicalrecordsfromyourearlierdoctor,andthisappointmentgivesusvaluableinformationaboutyourhealth.TheOutofHoursServiceisreachablefrom6:30p.m.until8a.m.MondaytoFriday;atweekendsfrom6:30p.m.Fridayto8a.m.Monday.Telephone0845-345-8995totalktotheOutofHoursService.Theywillhaveadoctorgetintouchwithyou.Formedicaladvice,youcancallNHSDirect（24hours）on0845-4647orthroughtheInternetatwww.nhsdirect.nhs.com.Youcanalwaysgetadviceoverthetelephone.Ifyouaretooilltocometothemedicalcentre,youcanaskforahomevisitoverthetelephone.Mostvisitsbydoctorsaremadebetween12noonand3p.m.Ifyouareabletophonebefore11a.m.,thishelpsustoplantheday.WhatcanbelearntfromParagraph1?
A.Thecentreopensallweekround.
B.octorsandnursesworksixhoursaday.
C.ppointmentsarenotacceptedintheafternoon.
D.same-dayappointmentmaynotbewiththeusualdoctor.
求下列函数的导数y=e2x2+x2；
设区域D为x2+y2≤4，（）
A.4π
B.3π
C.2π
D.π
WhenAnna_____theroom,agroupofyoungmenweretalkingeagerlyroundthetable.
A.enters
B.hasentered
C.wasentering
D.entered
DIamwatchingmysonandhundredsofhisclassmates,marchinginperfectorderintotheuniversityfootballstadium（体育场）.Holdingbackmytears,Isearchformysonintheseaofpeople.Suddenly,thereheis.Ijumptomyfeetandstartwaving.Armsflyingbackandforthabovemyhead,Ilooklikeawindmill（风车）,ormaybeanairportworkerguidingaplane.Iseehimsmile,thenlaughashepullshiscameraoutofhispocket.Hetakesapictureofmeashewavesback,andthengoestofindhisseat.Whatisitaboutgraduationsthatmakesthemsomoving?Whydomostofuswomencryaswewatchoursons,daughters,grandchildren,nieces,andnephewsmarchindarkrobes（长袍）?Wecrypartlybecause,nomatterhowoldourchildrenare,andnomatterhowmuchtheyhaveachieved,inoureyestheyarestillthelittlebabieswecarryaroundthehousetocomfort.And,ofcourse,wecryalsobecausesomethingwonderfulisending,andwemissitalready.Whateverisonitswaytotakeitsplacewillnotbethesame.Ithasbeensuchagifttohavemysongotocollegeclosetohome.Weneverhavetoworryaboutwhetherhewillbeabletomakethetriphomeforaholiday.Butthiswasatime-limitedgift.MysonwillattendgraduateschoolinCalifornia.Wewilltalkandtextlikecrazy,andvisitasoftenaswecan.Butitwillnotbethesame.Whomdoesthesontakeapictureofbeforetakinghisseat?
A.Peopleinthestadium.
B.nairportworker.
C.Hisclassmates.
D.Hismother.
Ithasbeenalmostfiveyears_____wesaweachotherlasttime.
A.after
B.before
C.since
D.when
肯定思维与存在具有同一性是()
A.形而上学观点
B.唯物主义观点
C.唯心主义观点
D.可知论观点
已知直线y=-2x+m不经过第三象限，则m的取值范围是_____。
BMariaMitchell（1818-1889）,thefirstwomanastronomer（天文学家）intheUnitedStates,wasborninNantucket,Massachusetts.Herparentsvaluededucationandinsistedongivingherthesamequalityofeducationthatboysreceived.Herfather,WilliamMitchell,wasanastronomerandteacherhimself.Whenhebuilthisownschool,Mariabecameastudentandalsoateachingassistanttohim.Athome,Maria'sfathertaughthertowatchthestarsandothernaturalobjectsinspaceusinghispersonaltelescope（望远镜）.LatershewenttoworkatthelibraryoftheNantucketAtheneum.Overthenexttwentyyears,shefurtherdevelopedherinterestinreadingasmanybooksasshecould.Shespenthernightswatchingtheskycloselywithherfather.OnOctober1,1847,Mafiadiscoveredacomet（彗星）bymerelyusingatwo-inchtelescope.Someyearsbefore,KingFrederickVIofDenmarkhadsetupprizestoeachdiscovererofa"telescopiccomet".Theprizewastobegiventothe"firstdiscoverer"ofeachsuchcometbecausecometswereoftendiscoveredbymorethanoneperson.Therewasonceaquestionofwhoshouldbethewinner.Asthestorygoes,FrancescodeVicohaddiscoveredthesamecomettwodayslater,buthadreportedittotheEuropeanofficialfirst.However,aftersomediscussionthiswassettledinMitchell'sfavor.Shewontheprizein1848andbecameabignametheworldover.Thecometwasnamed"MissMitchell'sComet".WhendidFrancescodeVicodiscoverthecomet?
A.In1818.
B.In1889.
C.In1848.
D.In1847.
设u=u(x，y)为可微函数，且当y-=x2时，有u(x，y)=1及∂u/∂x=x，则当y=x2(x≠0)时，∂u/∂y=()
A.1/2
B.-(1/2)
C.1
已知M，N为集合I的非空真子集，且M，N不相等，若N∩∁IM=ϕ，则M∪N是()
A.M
B.N
C.I
D.∅
∫20|1-x2|dx=_____．