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如图所示，当开关S闭合后，电流表A1、A2、A3的示数分别为1A、0.6A和1.2A，求L1、L2、L3中的电流分别为多少？
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已知图12-1所示正弦电流电路发生谐振时电流表A1A2的读数分别为4A和3A则电流表A3的读数为下
1A
7A
5A
不能确定
如图所示的电路图中电源两端电压始终不变把S1S2都闭合时电流表A1的示数为1安电流表A2的示数为0.
通过R1的电流为0.8安；
R2的阻值为8欧；
电源电压为1.6伏；
断开开关S1时，电流表A2的示数变大；
如图所示的电路中开关S.闭合后电压表VlV2的示数分别为12V.和4V.电阻R2=20Ω求电阻R1的
己知图12-1所示正弦电流电路发生谐振时电流表A1A2的读数分别为4A和3A则电流表A3的读数为下列
(A) 1A
(B) 7A
(C) 5A
(D) 不能确定
如图所示电路电源电压保持不变只闭合开关S.电流表的示数为0.2A再闭合开关S1电流表的示数变化了0.
那么闭合S.、S1后，R1与R2的电功率之比是（ ） A.2：3
3：2
5：2
1：2
.如图所示电路中当开关闭合后电流表A1A2的示数比I1I2=53则电阻比R1R2=______电流表
如图1.3-32所示正弦电流电路发生谐振时电流表A1A2的读数分别为4A和3A则电流表A3的读数为
1A
7A
5A
不能确定
在图所示的电路中电源电压不变闭合开关后电流表A1的示数为0.5A电流表A2的示数为0.3A则R.1∶
如图所示电源电压保持不变闭合开关S在滑动变阻器的滑片由中点向右移动的过程中下列说法错误的是
灯泡L的亮度不变
电流表A1示数变大
电流表A2示数变小
电压表V示数不变
在图所示的电路中电源电压不变闭合开关后电流表A1的示数为0.5A电流表A2的示数为0.3A.则R1R
已知题12图所示正弦电流电路中电流表的读数分别为A1为5AA2为20AA3为25A如果维持电流表A1
45.25A
25.5A
30.31A
40.31A
如图所示电路电源电压不变开关S闭合前电压表示数为6V开关S闭合后电流表A1的示数为0.6AA2的示数
下列判断正确的是 ( )
A.干路电流为1.1A
通过R1的电流为0.1A
电阻R2的电阻值为12
R2和R3交换位置后，电流表A1和A3的示数不变
如图所示的电路中电源两端的电压保持不变电阻R2与R3的阻值均为10Ω闭合开关S电流表A1和A2的示数
R1＝5Ω;
R1＝20Ω;
U1：U2＝3：4;
U1：U2＝4：3.
如图所示当开关闭合后电流表A１和A２的示数与开关闭合前相比较下列说法中正确的是
A１不变，A２增大;
A１和A２的示数都增大;
A１和A２的示数都减小;
A１减小，A２增大.
如图所示○A1和○A2是两个相同的电流表○V1和○V2是两个相同的电压表.电流表○A1的示数是1.4
如图所示电路电源电压恒定R.0为定值电阻R.为滑动变阻器.闭合开关S.后在滑动变阻器滑片P.向左滑动
电流表A1的示数变小
电流表A2的示数变大
电压表V的示数变小
电灯的亮度变暗
计算题下图所示电路中稳压管的稳定电压Uz=12V图中电压表流过的电流忽略不计试求1当开关S闭合时电压
如图所示电路中R1∶R2=12R2=12Ω闭合开关S后电流表A1的示数是O.5A电源电压是_____
如图所示的电路闭合S后电流表A1A2的示数分别为I1I2各示数间的关系为:
I1＝I2 ;
I1>I2;
I1
无法确定哪个大.
如图所示当开关S.闭合后电流表A.1A.2A.3的示数分别为1.2A1A0.6A则通过L.1L.2L
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已知fx＝f-1＝若fa＝1则实数a的值为．
已知函数fx＝3x2则fx在x＝3处的导数为
已知a＞b＞0则下列不等式正确的是
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已知向量＝x11＝410||＝则x＝•＝．
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已知双曲线＝1a＞0b＞0的一条渐近线方程为y＝-2x则此双曲线的离心率为
椭圆+y2＝1的长轴长为
MykidssitinGee'slivingroomandcautiouslyliftantiqueChristmasornaments饰品outofawell﹣lovedcardboardbox.Geestandsbesidethemquietly1eachtreasure.ShetellsmethatsheandTombuilttheirornament2piecebypieceduringeachyear'safter﹣Christmassale.She3asweleavewiththebox.Herprecioustreasuresgatheredoveralifetimehavefoundanew4. WefirstmetTomandGeeintheearlydaysofourmarriage.Someonehadbeen5ourgarbagecanstothegarageeachgarbagedayandJimandIhad6who.Thenonedaywe7himanelderlymanwholivedacrossthestreet. Ibakedcookiesandleftthemonastooloutsidethegaragewithathank﹣younote.Whenwegothomefromworkthatdayatypedletterhad8thegift.TheletterwasfromTomandexplainedhowhehadcometowalktheneighborhoodongarbagedayreturningcansforpeoplehe9knew.Backwhenhe'dbeenfightingawarIwasn't10toseehisyoungwifeGeehadfoundherselflivingalone.Neighborshadtakenthetimetohandlehergarbagecans11shedidn'thavetoandheneverforgot.Nowhe12itforwardbydoingthesameforallofus. Afewyearsafterwe'dmovedinTom13.Wephotocopiedthat14andattachedittooneofourownforGee.Wetoldherhow15Tomhadbeentousandhowwegrievedforher.Shewrotebackandtoldusshe16talkedtoTomeveryday.WhenGeeinvitedusovertolookthroughChristmasornamentsIrealizedhowharditmustbeto17withthatboxapieceofTom. JimandIagreeto18ourtreewithGee'sornamentsthisChristmasoutoftheboxthatis19inTom'shandwriting.MaybeI'lltalktohimjustasGeestilldoes.ThankyouI'llsayforteachinguswhatit20tobeaneighbor. 1A.confirming B.explaining C.revealing D.touching 2A.shelf B.basement C.art D.collection 3A.smiles B.weeps C.sighs D.hesitates 4A.home B.destination C.function D.chance 5A.distributing B.exposing C.returning D.attaching 6A.discovered B.wondered C.foreseen D.investigated 7A.spotted B.impressed C.acknowledged D.grasped 8A.answered B.replaced C.delivered D.rewarded 9A.especially B.thoroughly C.previously D.barely 10A.willing B.voluntary C.alive D.keen 11A.so B.before C.because D.if 12A.brought B.carried C.paid D.pushed 13A.survived B.withdrew C.retired D.died 14A.note B.gift C.letter D.treasure 15A.grateful B.close C.special D.superior 16A.still B.even C.just D.ever 17A.live B.finish C.go D.part 18A.supply B.manage C.decorate D.arm 19A.drafted B.labeled C.signed D.preserved 20A.reflects B.desires C.anticipates D.means
用数学归纳法证明“1-+-+…+＝n∈N*”第一步应验证的等式是从“n＝k”到“n＝k+l”左边需增加的代数式是
已知F为抛物线y2＝4x的焦点过点F且斜率为1的直线交抛物线于AB两点设|FA|＞|FB|则＝．
若函数fx＝mx3+2x2-3x-1存在单调递增区间则实数m的值可以为
Someoftheworld'smostfamousmusiciansrecentlygatheredinParisandNewOrleanstocelebratethefirstannualInternationalJazzDay.UNESCOUnitedNationsEducationalScientificandCulturalOrganizationrecently1April30asadaytoraiseawarenessofjazzmusicitssignificanceanditspotentialasaunifying联合voice2cultures. Despitethecelebrations3intheU.S.thejazzaudiencecontinuesto4andgrowolderandthemusichasfailedtoconnectwith5generations. It'sJasonMoran'sjobtohelpchangethat.AstheKennedyCenter'sartistic6forjazzMoranhopesto7theaudienceforjazzmakethemusicmore8andpreserveitshistoryandculture. Jazzseemslikeit'snotreallyapartoftheAmerican9MorantellsNationalPublicRadio.WhatI'mhopingtoaccomplishisthatmygenerationandyoungerstartto10andunderstandthatjazzisnotblackandwhiteanymore.It'sactually11andit'sactuallydigital. Moransaysoneofthe12withjazztodayisthattheentertainmentaspectofthemusichasbeenlost.Themusiccan'tbe13todaythewayitwasin1908or1958.Ithastocontinuetomovebecausethewaytheworldworksis14saysMoran. LastyearMoranworkedonaprojectthat15FatsWaller'smusicforadancepartyjusttokindofputitbackinthemindthatWallerisdancemusic16itisconcertmusicsaysMoran.Formeit'stherecontextualization情景重构.Inmusicwheredoesthe17lie?Areweashumansgainingany18intohowwetalkaboutourselvesand19somethingasabstractasaCharlieParkerrecordgetsusintoadialogueaboutouremotionsandourthoughts?SometimeswelosesightthatthemusichasawidercontextsaysMoransoIwanttocontinuethose20. 1A.saluted B.set C.marked D.laid 2A.through B.around C.across D.outside 3A.regardless B.thus C.though D.rather 4A.expand B.boycott C.extend D.shrink 5A.younger B.smaller C.elder D.larger 6A.inventor B.adviser C.visitor D.officer 7A.widen B.strengthen C.enforce D.enrich 8A.available B.admirable C.avoidable D.accessible 9A.category B.appeal C.appetite D.recipe 10A.reconstruct B.reshape C.restore D.reconsider 11A.colorful B.meaningful C.creative D.sensitive 12A.connections B.problems C.satisfactions D.conflicts 13A.described B.revealed C.presented D.exposed 14A.transferring B.changing C.recovering D.processing 15A.managed B.arranged C.conveyed D.conducted 16A.asmuchas B.aslongas C.asfaras D.assoonas 17A.reality B.emotion C.melody D.future 18A.comprehension B.access C.appreciation D.insight 19A.why B.which C.how D.what 20A.trends B.dialogues C.messages D.contexts
已知抛物线y2＝4x过焦点F作斜率为k1的直线交抛物线于AB两点．1若|AB|＝5求k1．2过焦点F再作斜率为k2的直线交抛物线于CD两点且MN分别是线段ABCD的中点若k1+k2＝1证明直线MN过定点．
已知向量满足||＝1||＝||•＝0．若对每一确定的||最大值和最小值分别为mn则对任意m-n的最小值是．
函数fx＝4-2cosx的最小值是取得最小值时x的取值集合是．
复数z＝1-ii为虚数单位的虚部为
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