[单选题]在△ABC中,AB=5,BC=7,AC=8,则的值为( )A.79B.69C.5D.-5
[单选题]He looked at the envelope(信封) and _____ Jenny’s handwriting immediately. A.realizedB.recognizedC.reminded D.remembered
[单选题]下列命题中,假命题是( )A.Vx∈R.32-2>0B.Vx∈22(x-2)2>0C.彐x∈R.1gxo <2D.彐x∈R.tanx=2
[单选题]在△ABC中,AB=1,AC=3,D是BC边的中点,则ADBC=( )A.4B.3C.2D.1
[单选题]________, Im glad you made that mistake, for it will serve as a warning to you.A.In caseB.In a wayC.In returnD.In relief
[单选题]在△ABC中,角、B、C所对应的变分别为、、,则a≤b是sinA≤sinB的( )A.充分必要条件B.充分非必要条件C.必要非充分条件D.非充分非必要条件
[单选题]Since the early nineties, the trend in most businesses has been toward on-demand, always-available products and services that suit the customer’s ________ rather than the company’s.A.benefitB.availabilityC.suitabilityD.convenience
[计算题]已知点A(cosx,1+cos2x),B(﹣λ+sinx,cosx),x∈(0,π),向量=(1,0).(1)若向量BA与共线,求实数x的值;(2)若向量BA⊥,求实数λ的取值范围.
[单选题]According to statistics, a man is more than twice as likely to die of skin cancer _____a woman.A.thanB.suchC.soD.as
[单选题]A.l the students were eager to know what the future may have________for them when they graduatedFrom the school.[ ]A. in storeB. in commonC. in allD. in particular
[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
[单选题]Even within China, the beauty and mystery of Chinese food has never been properly explained or _____ appreciated on an artistic level.A.simply B.causallyC.brieflyD.thoroughly
[单选题]Thousands of athletes _______ in many countries competed ________ medals in the 2008 OlympicGames in Beijing. [ ]A.will involve ; in B.involving; byC.involved; against D.involved; for
[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
[计算题]设P:4x-3≤1,命题g:x2-(2a+1x+a(a+1)≤0,若“”为假命题,“”为真命题,求实数的取值范围.
[单选题]已知下列三个命题: ①棱长为2的正方体外接球的体积为4√3丌;②如果将一组数据中的每一个数都加上同一个非零常数,那么这组数据的平均数和方差都改变;③直线x-√3y+1=0被圆(x-1)2+y4截得的弦长为23.其中真命题的序号是(? ).A.①②B.②③C.①③D.①②③
[单选题]The digging will seem easier if you divide up the garden by marking ________ small sections with your spade (铲子). [ ]A. downB. upC. outD. with
[单选题]△ABC中,D是BC中点,AD=m,BC=n,则ABAC等于( )A.27224B.×WC.2m12+n4D.令
[单选题]已知命题p:x1,x2∈R,(f(x2)-f(x1))(x2-x1)≥0,则是 A.x1,x2∈R,(f(x2)-f(x1))(x2-x1)≤0 B.x1,x2∈R,(f(x2)-f(x1))(x2-x1)≤0 C.x1,x2∈R,(f(x2)-f(x1))(x2-x1)<0 D.x1,x2∈R,(f(x2)-f(x1))(x2-x1)<0
[计算题]在一次模拟射击游戏中,小李连续射击了两次,设命题:“第一次射击中靶”,命题:“第二次射击中靶”,试用,及逻辑连结词“或”“且”“非”表示下列命题:(1)两次射击均中靶; (2)两次射击均未中靶;(3)两次射击恰好有一次中靶;(4)两次射击至少有一次中靶.
[单选题]命题“x>0.x2+x>0”的否定是 ( )A.彐x>0,使得x2+x>0B.彐x>0,使得x2+x≤0C.x>0,都有x2+x≤0D.x≤0,都有x2+x>0