[单选题]已知O为原点,点A,B的坐标分别是(a,0),(0,a),其中常数a>0,点P在线段AB上,且
(0≤t≤1),则
的最大值为A、a2B、a C、2a D、3a
[单选题]已知圆O的半径为1,PA.PB为该圆的两条切线,A、B为两切点,那么的最小值为[ ]A.-3+22B.-3+2C.-4+22D.-4+2
[单选题]The committee asked for these suggestions to be ______ on paper, so that they might study them further.A.brought downB.handed downC.laid downD.put down
[单选题]已知m,n表示两条不同直线,α,β,γ表示不同平面,给出下列五个命题:①；②；③；④；⑤α⊥γ,β⊥γα∥β.[ ]A.0B.1C.2D.3
[单选题]The little child didn’t understand the ____ question so there was a ____ expression on his face.A.puzzling, puzzledB.puzzle, puzzledC.Puzzling, puzzlingD.puzzled, puzzling
[单选题]More than 300 years ago, the British used “fall” instead of? “______”.A.springB.summerC.autumnD.winter
[单选题]Messi’s talents _____ in comparison with other football players.A.stand outB.make outC.break outD.set out
[单选题]已知向量a=(1,2),向量b=(x,-2),且a⊥(a-b),则实数x等于A.9B.4C.0D.-4
[单选题]I intended to catch the early train, but I didnt get up______. [ ]A. at a timeB. at one timeC. in timeD. in no time
[单选题]Some students have troublegrammar while others have difficultynew words.A.in；rememberB.for；to rememberC.on；rememberingD.with；remembering
[单选题]已知a=(2+10.2A),b=(624-12),若a∥b则与的值分别为( )A.2B.5,2C.52D.-5,-2
[单选题]If you hurry up, I think it is quite ____ that you will catch the flight to Hong Kong . There are 40 minutes left.A.probablyB.likelyC.possiblyD.certainly
[单选题]A.though he is often tired ________ his work, he is never tired ________ his job. In fact, he enjoys it.[ ]A.of; withB.with; fromC.with; ofD.at; with
[单选题]下列命题中,真命题是A.?x0∈R,?≤0 B.?x∈R,2x＞x2 C.a+b=0的充要条件是=-1 D.a＞1,b＞1是ab＞1的充分条件
[单选题]— My computer _______ start, no matter how hard I try.— It might have crashed.A.won’tB.shouldn’tC.mustn’tD.wouldn’t
[单选题]I hope that my father will quit smoking because I want him to livemy grandpa does.A.as a long and healthy life asB.so long and healthy a life asC.such long and healthy a life asD.as long and healthy a life as
[单选题]The government will begin a series of ?to help the public fully understand the new educational system.A.expectationsB.occasionsC.presentationsD.assumptions
[单选题]已知点G是△ABC的重心,若∠A=120°,4B●AC=-2,则AG的最小值是( )A.33B.22C.23D.34
[单选题]-How do you think he managed to improve his English in such a short time-______ four hours on it every day.[ ]A.Because of spendingB.To spendC.By spendingD.Spending
[单选题]在直角坐标系xOv中,、分别是与轴,轴平行的单位向量,若直角三角形ABC中,AB=2i+j,AC=3i+k,则的可能值有( )A.1个B.2个C.3个D.4个
[单选题]设P={x∈R|-≥1,Q={x∈Rln(1-x)≤0,则“x∈P”是“x∈”的 ( )A.必要不充分条件 B.充分不必要条件C.必要条件D.既不充分也不必要条件