[单选题]已知向量a=(3,4),b=(2,-1),如果向量a+λb与b垂直, 则λ的值为A.B.-C.D.-
[计算题]设p>0是一常数,过点Q(2p,0)的直线与抛物线y2=2px交于相异两点A、B,以线段AB为直经作圆H(H为圆心),试证抛物线顶点在圆H的圆周上;并求圆H的面积最小时直线AB的方程.
[单选题]I am gratefulyouyour kind offer.A.to;forB.for;toC.to;toD.for;for
[单选题]已知△ABC平面内一点P满足PA+PB+PC=0,若实数满足:AB+AC=AP,则的值为( )A.6 B.3 C.2 D.
[单选题]When more and more women join the WHO, it takes on a new look—as news reports put _____.A.itB.thatC.soD.one
[计算题]把下列命题改写成“若p ,则q”的形式,并写出它们的逆命题、否命题与逆否命题,同时指出它们的真假.(1) 全等三角形的对应边相等;(2) 当x=2时,x2-3x+2=0 .
[单选题]The _____ in temperature is broadcast twice a day in the channel.A.diversionB.varietyC.variationD.diversity
[计算题](本小题满分12分)已知平面上三点,,.(1)若(O为坐标原点),求向量与夹角的大小;(2)若,求的值.
[单选题]给出下列命题:(1)“若,则x. L互为倒数”的逆命题;(2)“面积相等的三角形全等”的否命题; (3)“若m≤1,则x2-2x+m=0有实根”的逆否命题;(4)“若A∩B=B,则AcB”的逆否命题.其中为真命题的是( )A.(1)(2)B.(2)(3)C.(1)(2)(3)D.(3)(4)
[单选题]It can’t be a(n) __________that another big fire broke out in the same restaurant in three months.A.accidentB.incidentC.chanceD.coincidence
[单选题]若命题p:0是偶数,命题q:2是3的约数,则下列命题中为真的是[ ]A.p且qB.p或qC.非pD.非p 且非q
[单选题]“|x|<2”是“x2﹣x﹣6<0”的[ ]A.充分而不必要条件B.必要而不充分条件C.充要条件D.既不充分也不必要条件
[单选题]若aR,则a=2是(a-1)(a-2)=0的(?)A.充分而不必要条件 B必要而不充分条件C.充要条件 C.既不充分又不必要条件
[单选题]The bank is equipped with new alarm. We can say its safe and reliable completely. AmethodB.wayC.orderD.system
[单选题]下列四个命题:①利用计算机产生0~1之间的均匀随机数,则事件“3a-1>0”发生的概率为1-3;②“x+v≠0”是“x≠1或J≠-1”的充分不必要条件; ③命题“在△ABC中,若sin A=sin B,则△ABC为等腰三角形”的否命题为真命题;④如果平面不垂直于平面,那么平面内一定不存在直线垂直于平面.其中说法正确的个数是( )A.0个B.1个C.2个D.3个
[单选题]We had expected sales to pick up at the beginning of this year 2011, but it was?our imagination _____ that it would be this good.[ ]A. beyond B. withoutC. outside D. through
[计算题]已知A、B、C的坐标分别为A(3,0),B(0,3),C(cosα,sinα),.(Ⅰ)若||=||,求角α的值; (Ⅱ)若,求的值.
[单选题]Increased production will,________,lead to increased profits.[ ]A.in natureB.in frontC.in turnD.in fact
[单选题]空间任意四个点A、B、C、D,则CB+ BA-CD等于 ( )A.DB B.AD C.DAD.AC
[单选题]已知点A(,1),B(0,0),C(,0),设∠BAC的平分线AE与BC相交于E,那么有,其中λ等于 ( )A、2B、C、-3D、
[单选题]Nowadays, many people walk to workCopenhagen Conference calling for living alow-carbonlifestyle to cope with global warning. [ ]A. in relation to B. in response to C. in addition to D. in opposition to