[单选题]已知平面向量=(2,4),=(-1,2),若=-(·),则||等于A、4B、2C、8D、8
[单选题]In fact , the old couple looked forward every week ?___ their grandson . [ ]A. to see B. to seeing C. see D. seeing
[单选题]There, a big memorial has been built______ him, who devoted himself to the poor.A.in favor ofB.in memory ofC.in face of D.in need of
[单选题]设{an}是等比数列,则“a1<a2<a3”是“数列{an}是递增数列”的[ ]A.充分不必要条件B.必要不充分条件 C.充分必要条件D.既不充分又不必要条件
[单选题]下列命题中是假命题的是 ( )A.α,β∈R,使cos(α+β)=cosα+sinβB.>0,有ln2x+lnx+1>0C.,使幂函数,且在(0,+)上递减 D.,函数y=sin(2x+φ)都不是偶函数
[单选题]已知向量i=(1,0),j=(0,1),a=i-2j,b=i+λj,且a与b的夹角为锐角,则实数λ的取值范围( )A.(-∞,-2)∪(-2,2)B.(-∞, 2)C.(-2,2)D.(-∞,-2)
[单选题]-- Can you lend me the book Twilight by Stephenie Meyer-- Sorry. I returned it to the library just now. Maybe it is still _____.A.availableB.affordableC.acceptableD.valuable
[单选题]Everybody present at the party was shocked at her violent reaction ______ the young man’s presence. [ ]A. withB. toC. forD. by
[单选题]______ all the texts that are written, stored and sent electronically, a lot of them are still ending up on paper.A.ForB.FromC.ExceptD.By
[单选题]It is believed that the tight employment market has forced job seekers to_______whatever work is available.A.take upB.take downC.take offD.take on
[单选题]设{an}是等比数列,则“a1<a2<a3”是“数列{an}是递增数列”的[ ]A.充分不必要条件B.必要不充分条件 C.充分必要条件D.既不充分又不必要条件
[单选题]— I heard the phone ringing in the office next door. — You _______ it. They haven’t got a phone yet.A.couldn’t hearB.couldn’t have heardC.didn’t hearD.wouldn’t have heard
[单选题]All present were shocked by what the little boy______ when he was cheated and sold to the mountain village.A.cared aboutB.got along withC.went throughD.came up
[单选题]“m=-1”是“函数f(x)=ln(mx)在(-∞,0)上单调递减”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]We met an old friend in New York ____our expectation. She waved at us _____ the street when she saw us.A.with; in B.out of; next toC.in; out ofD.beyond; from across
[单选题]已知命题p:3≥2,命题q:函数f(x)=x2-x在区间[0,+∞)上单调递增,则下列命题中为真命题的是 ( )A.∨q B.p∧q C.D.p∨q
[计算题]已知点P(2cosα,2sinα)和Q(a,0),O为坐标原点,当a∈(0,π)时,(Ⅰ)若存在点P,使得PO⊥PQ,求实数a的取值范围;(Ⅱ)如果a=-1,设向量与的夹角θ的最大值.
[单选题]—Oh, doctor, The wound on my leg is infected. —You really shouldn’t have left it _______ to the sun. A.discoveredB.exposedC.openedD.buried
[单选题]Most parents think there are differences in their approach _______ their children compared with thatof their parents.[ ]A. to educate B. about educatingC. to educatingD. of educating
[单选题]It was unfortunate that their new car ____ halfway to the airport.A.broke offB.got overC.broke downD.got away
[单选题]Last night, your mobile phone was always busy. I couldn’t ______ to you after several attempts. A.go overB.get throughC.get alongD.go through