[单选题]已知椭圆的左、右焦点分别为F1、F2,点M在该椭圆上,且=0,则点M到y轴的距离为( )A.B.C.D.
[单选题]“b2=ac”是“a,b,c成等比数列”的[ ]A.充分不必要条件B.必要不充分条件C.充要条件 D.既不充分也不必要条件
[单选题]My friend, Darren, is coming to visit us. Im looking forward____? him.[ ]A. meetB. meeting C. to meet D. to meeting
[单选题]The tiger, once a ____ animal to humans, is now ____of disappearing on the earth.A.dangerous, danger B.in danger, in dangerC.dangerous, in dangerD.danger, in danger
[单选题]It took quite a while to sort all our luggage.[ ]A. ofB.outC.upD.in
[单选题]下列命题中,为真命题的是( )A.彐x∈[—2丌]sinx-cosx≥2B.vx∈R.x2<xC.vx∈0.-.tanx>sinxD.三x∈R.x2+x=-1
[单选题]给出下列四个命题,其中正确的命题的个数为[ ] ①命题“存在x0∈R,2x。≤0”的否定是“.对任意的x∈R,2x>0”;②函数ytan的对称中心为(kπ,0),k∈Z;③1082sir12+1082cos=﹣2;④[cos(3﹣2x)]=﹣2sin(3﹣2x).A.1B.2C.3D.4
[单选题]The jewels that the rich lady was wearing that evening must be ______.A.cost fortune B.worth a fortuneC.cost a fortune D.worth fortune
[单选题]下列命题中的假命题是( )A.x∈R,2x->0B.vx∈N,(x-1)2>0C.三x∈R,1gx<1D.三x∈R,tanx= 2
[单选题]已知O为△A.C的重心,设,则= [ ]A.B.C.D.
[单选题]The teachers were always trying to ______ the excited students at that time.A.calm down B.set down C.let down D.turn down
[单选题]My brother gave me a present for my birthday but I gave him nothing ______ his.A.in returnB.by turnsC.in turnD.in return for
[单选题]There is no doubt_______ English is the widely used language all over the world.A.thatB.whetherC.ifD.how
[单选题]若非零向量a,b满足|a+b|=|b|,则 [ ]A、B、C、D、
[单选题]She changed so much that I could hardly _____ her when we met again after a separation of 20 years. What’s more, she had just had her hair cut, and she was wearing new glasses.A.recognize B.knowC.rememberD.tell
[单选题]Yosemite National Park has the best collection of native plants. ______, it contains a great number of trees and flowers from overseas.A.In additionB.In returnC.In rewardD.In reality
[单选题]_____ fire, all safety rules must be kept clear.A.In place ofB.Instead ofC.In case ofD.In spite of
[单选题]若、为空间两条不同的直线,、为空间两个不同的平面,则a⊥a的一个充分条件是( )A.a∥B且a⊥BB.ac且a⊥BC.a⊥b且bllD.a⊥B且a∥B
[单选题]_______the Teachers’ Day ,the students are cleaning the classroom.A.In spite ofB.In celebration ofC.In search ofD.In place of
[单选题]Any help from you will be greatly appreciated. Please give me a reply at your earliest.A.interruptionB.instructionC.considerationD.convenience
[单选题]如图,四面体ABCD中,点E是CD的中点,记AB=a,AC=b,AD=c,则BE=CA.2+2B.+2+2C.2+2D.2++2