[单选题]在△ABC中,,∠A=,则k的值为( )A、B、C、D、
[单选题]以下有关命题的说法错误的是( )A.命题“若x2-3x+2=0,则x=1”的逆否命题为“若x≠1,则x2-3x+2≠0” B.“x=1”是“x2-3x+2=0”的充分不必要条件 C.对于命题p:,使得x2+x+1<0,则,均有x2+x+1≥0 D.若p∧q为假命题,则p、q均为假命题
[单选题]You should have been more patient________that customer;Im sure that selling him the watch wasa possibility. [ ]A. of B. withC. forD. at
[单选题]Glancing ______ his shoulder, Eric could see the dog was running after him.A.overB.acrossC.throughD.onto
[单选题]________ of the land in that district(地区) _______ covered with trees and grass.A.Two fifth; isB.Two fifth; areC.Two fifths ; is D.Two fifths; are
[单选题]Frank was offered a job in a bank, but________our surprise, he didnt take it.( )A.toB.atC.forD.in
[单选题]I have some trouble ______reading the letter. His handwriting is very bad.[ ]A. in B. of C. with D. on
[单选题]“α=2kπ+β,k∈Z”是“sinα=sinβ”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
[单选题]My pen friend and I keep in touch ________ sending e-mails often. [ ]A. with B. by C. onD. of
[单选题]已知命题p:Vx∈R22<3;命题g:3x∈R,x3=1-x2,则下列命题中为真命题的是( )A.p AgB.p∧-qC.p∧qD.P∧-q
[计算题]命题p:x∈R,x2<a,命题q:ax2+x+1>0恒成立.若p∨q为真命题,p∧q为假命题,求a的取值范围.
[单选题]The work is not very profitable(盈利的) _______ cash(现金), but I am getting valuable experience from it.A.in terms ofB.according toC.in relation toD.in view of
[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]原命题p?:“设a、b、c∈R若a>b则ac2>b2C”以及它的逆命题,否命题、逆否命题中,真命题共有( )个.A.0 B.1 C.2 D.4
[单选题]Many students listened to the lecture, but I wondered how much work they took________. [ ]A. outB. up C. offD. in
[计算题]如图,在平行四边形ABCD中,AD=2AB=2,∠BAD=60°,M、N分别是对角线BD、AC上的点,AC、BD相交于点O,已知BM=BO,ON=OC,设向量=a,=b,(1)试用a,b表示;(2)求||.
[单选题]Don’t give up halfway, Andy. You’ll succeed _______ if you keep on working like this.A.in turnB.on timeC.in timeD.by accident
[单选题]给定两个命题,.若2是的必要而不充分条件,则是的( )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]Harry ismy neighbour. He is also a good friend of mine.[ ]A. less thanB. at leastC. at most D. more than
[单选题]Sometimes proper answers are not far to seek________food safety problems.[ ]A.inB.toC.onD.after
[单选题]______addition to being creative, perseverance and diligence are necessary qualities to be a good scientist.[ ]A. WithB. OfC. In D. For