[单选题]在△ABC中,已知,则∠B等于A.60°B.120°C.30°D.150°
[单选题]Jeremy Lin is a man with a strong will. After repeated_______ he finally succeeded in his career.A.announcementsB.decisionC.remarksD.attempts
[单选题]曲线x2+y2+Dx+Ey+F=0经过原点的充要条件是( )A.D=0 B.E=0C.F=0 D.以上都不对
[单选题]“k=1”是“直线x-y+k=0与圆x2+y2=1相交”的[ ]A.充分而不必要条件B.必要而不充分条件C.充分必要条件 D.既不充分也不必要条件
[单选题]下列说法错误的是( )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.命题p“存在x∈R,使得x2+x+1<0”则p:“任意x∈R,均有x2+x+1≥0C.若a≠0则“a'c=ab”是“bc”的充要条件D.若“p且q” 为假命题,则p, q至少有一个为假命题
[单选题]“x>0”是“x≠0”的?[ ]A.充分而不必要条件B.必要而不充分条件C.充分必要条件D.既不充分也不必要条件
[单选题]It is nice to do something for someone else out of the blue and not to expect anything ______.A.in reliefB.in return C.in turnD.in need
[单选题]“|x|<1”是“In x<0”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]The big building _____ construction will be a shopping mall in the city.A.inB.underC.overD.during
[单选题]I finished the work several days the deadline.[ ]A. ahead of B. in front ofC. in the face ofD. in favor of
[单选题]设p:0<x<1q:(x-a)[x-(a+2≤0若p是q的充分而不必要条,则实数a的取值范围是 ( )A.[-10B.(-10)C.(-∞20]U1+∞D.(-∞2-1)U(02+∞)
[单选题]------Have you known each other for long------ Not very, ________we started to work in the ABC Motor Company.A.before B.sinceC.whenD.after
[单选题]--- Is this the first time you ___ Xiamen --- No. But the first time I ____ here, the city wasn’t so beautiful.A.visited, comeB.visited, have comeC.have visited, cameD.have visted, have come
[单选题]The suit _______him quite well_______the color was a little brighter. A.fit; except thatB.fitted; except forC.matched; besidesD.suited; aside from
[单选题]已知平面上直线l的方向向量,点O(0,0)和A(1,-2)在l上的射影分别是O1和A1,则,其中λ= [ ]A、 B、- C、2 D、-2
[单选题]Your daughter passed the piano exam excellently, ________, she did very well in the exam. [ ]A. in the endB. on the other handC. in other wordsD. at the same time
[单选题]设x∈R?,向量a=(x1).b=(1-2)且a⊥b?,则l a+b( )A.B.√10C.2√5D.10
[单选题]He looks younger ______ his friend; in fact, he is three years senior _______ his friend.A.to; toB.than; byC.than; thanD.than; to
[计算题]如图所示,已知圆C:(x+1)2+y2=8,定点A(1,0),M为圆上一动点,点P在AM上,点N在CM上,且满足,点N的轨迹为曲线E,(1)求曲线E的方程;(2)过点S(0,)且斜率为k的动直线l交曲线E于A、B两点,在y轴上是否存在定点G,满足使四边形NAPB为矩形?若存在,求出G的坐和四边形NAPB面积的最大值;若不存在,说明理由.
[单选题]设x是实数,则“x>0”是“|x|>0”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]The wine industry in the area has developed in a special way, _________little foreign ownership. [ ]A. by B. ofC. with D. from