[单选题]设向量a与b的夹角为θ,定义a与b的“向量积”:a·b是一个向量,它的模|a·b|=|a|·|b|·sinθ,若a=(-,-1),b=(1,)则|a·b|=A.B.2C.2D.4
[单选题]Alice trusts you ; only you can____her to give up the foolish idea.A.insistB.adviseC.sufferD.persuade
[单选题], I lost heart in English learning, but my teacher often said to me, Keep on studying hard ,and youll succeed .[ ]A. At one time; in timeB. At one time; on timeC. At a time; in timeD. At a time; on time
[单选题]“a=2”是“直线(a2-a)x+y=0和直线2x+y+1=0互相平行”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]“72”是“直线x+m\v=0与直线Xv=垂直”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]In order to catch the movie, Mary finished her supper in ________ ten minutes.[ ]A.less thanB.more thanC.lessD.more
[单选题]He goes to work every day ______.A.except for rainy daysB.besides it rainsC.but that it rainsD.except on rainy days
[单选题]Our efforts resulted________failure.I think Im also responsible________it.[ ]A. in; toB. from; toC. in; forD. from; for
[单选题]下列说法中正确的是[ ]A.一个命题的逆命题为真,则它的逆否命题一定为真B.“a>b”与“a+c>b+c”不等价C.“a2+b2=0,则a,b全为0”的逆否命题是“若a,b全不为0,则a2+b2≠0”D.一个命题的否命题为真,则它的逆命题一定为真
[计算题]平面向量(3,-4),b=(2,x),c(2,y),已知∥,a,求x,y的值.
[计算题]指出下列各组命题中,p是q的什么条件(1)p:(x-2)(x-3)=0;q:x-2=0.(2)p:四边形的对角线相等;q:四边形是平行四边形.(3)p:m<-2,q:方程x2-x-m=0无实根.
[单选题]The?lion?is?considered?the?king?of?the?forest?as?it?is?a(n)?____of?courage?and?power.A.exampleB.signC.markD.symbol
[单选题]I am________your suggestion________we should spend more time on this project.[ ]A. in favour of; whichB. in honor of; thatC. in favour of; thatD. in honor of; which
[单选题]With the word PM2.5______ heard and seen in our life, people become more and more concerned about air pollution.A.constantly B.occasionallyC.consequently D.contemporarily
[单选题]若四边形ABCD满足,则该四边形一定是( )A.正方形B.矩形 C.菱形D.直角梯形
[单选题]It was from John, ____ gave me a big key to _____ my dad.A.who; understandBthat; understandingC.who; understandingD.which; to understand
[单选题]Emily is easy to be ______ as shes the only one of the women who is wearing evening dress.A. realisedB.respectC. recognisedD.refused
[单选题]下列命题中,真命题是[ ]A. 若||=||,则=或=-B. 若=,=,则=C. 若∥,∥,则∥D. 若,则A、B、C、D是一个平行四边形的四个顶点
[单选题]The teacher asked the students to do the experiment __________ small groups.A.toB.forC.onD.in
[单选题]You’ve got to decide where you stand on this issue ---you’re either _____ me or against me.[ ]A. toB. onC. withD. at
[单选题]a=0是复数Z=a+bi(a,b∈R)为纯虚数的( )A.充分条件但不是必要条件B.必要条件但不是充分条件C.充要条件D.既不是充分也不必要条件