[单选题]已知向量a=(2,1),b=(-1,k),a·(2a-b)=0,则k=A.-12B.-6C.6D.12
[单选题]Finding a job in such a big company has always been________his wildest dreams.[ ]A. underB. overC. aboveD. beyond
[单选题]________theEnglishbeginnersintheclasshave some difficulty with English. but I believethey will get over it.[ ]A. At the momentB. For a momentC. From the moment onD. The moment
[单选题]You’d better give the plant a bit of water every now and then to keep it ____ too dry.[ ]A. to getB. gotC. gettingD. from getting
[单选题]已知m,n表示两条不同直线,α,β,γ表示不同平面,给出下列五个命题:①;②;③;④;⑤α⊥γ,β⊥γα∥β.[ ]A.0B.1C.2D.3
[单选题]若向量、满足,=√2,且a⊥(a+b,则与的夹角为( )A.—2B.2丌3C.3丌4D.5丌6
[单选题]P是△A.C所在平面上一点,若PA·PB=PB·PC=PC·PA,则P是△ABC的[ ]A.外心 B.内心 C.重心 D.垂心
[单选题]对于以下判断:(1)命题“已知x.v∈R”,若x2或y3,则x+y5”是真命题.(2)设f(x)的导函数为f(x),若f(x0)=0,则x0是函数f(x)的极值点.(3)命题“vx∈R,ex﹥0”的否定是:“彐x∈R,ex﹥0”.(4)对于函数f(x),g(x),f(x)g(x)恒成立的一个充分不必要的条件是f(x)ming(x)max.其中正确判断的个数是( )A.1B.2C.3D.0
[单选题]According to media reports, the London stadium is ?other Olympic stadiums in terms of steel used.A.as 75% light asB.75% lighter asC.75% lighter thanD.as light as 75%
[单选题]设a b是平面内两条不同的直线,是平面外的一条直线,则\l⊥a且1⊥b是\⊥a\的( )A.充要条件B.充分不必要条件C.必要不充分条件D.既不充分也不必要条件
[单选题]设命题P:m≥,命题q:一元二次方程x 2+x+m=0有实数解.则p是q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
[计算题]二.解答题:(计90分)(本题满分14分)已知两个命题r(x):sinx+cosx>m;s(x):x2+mx+1>0.如果对于任意实数x,r(x)s(x) 为假,r(x)s(x)为真,求实数m的取值范围.
[单选题]Modern China is experiencing a completely new period ________ respect for science and creativityhas become the guiding principle of society. [ ]A. of whichB. whereC. in whichD. that
[计算题](1)如图,证明命题“a是平面π内的一条直线,b是π外的一条直线(b不垂直于π),c是直线b在π上的投影,若a⊥b,则a⊥c”为真.(2)写出上述命题的逆命题,并判断其真假(不需要证明).
[单选题]I was deeply impressed ________ the speech by the mayor of Shanghai before the final voting for EXPO 2010.A.toB.onC.overD.with
[单选题]--- How did you react _____ your fathers suggestion --- I reacted strongly _____ it .A.on; toB.on ; withC.against ; withD.to ; against
[单选题]设x,y∈R,P:x+y≠5,Q:x≠2或y≠3,则P是Q的[ ]A.充分不必要条件B.必要不充分条件C.既不充分又不必要条件D.充要条件
[单选题]已知两点M(-2,0),N(2,0),点P满足,则点P的轨迹方程为A.B.x2+y2=4C.y2-x2=8D.x2+y2=8
[单选题]— May I speak to Mr Smith — I am afraid not. He is at a meeting now. It’s not ___.A.reliableB.convenientC.beneficialD.available
[单选题]已知平面向量→a,→b,满足a=2,b|=3,a-(a-2b)=0,则rab=(?)A.2B.3C.4D.6
[单选题]已知数列fa,那么“对任意的n∈N,点P,(n, a,)都在直线y=2x+1上”是“fa为等差数列”的( )A.必要而不充分条件B.既不充分也不必要条件C.充要条件 D.充分而不必要条件