[单选题]下列命题正确的是( )
A.若=,则⁼
B.若|+|=|-|,则=0
C.若//,//,则//
D.若与是单位向量,则=1

• [单选题]Sally is always looking in the mirror, _______herself.A.enjoyingB.respectingC.admiringD.behaving

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• [单选题]We were alarmed at the way in which John reacted________the drug.[ ]A.againstB.on C.to D.with

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• [单选题]已知向量,若a∥b,则λ的值为[ ]A.-2 B.C.D.

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• [单选题]已知e1e是两夹角为120°的单位向量,a=3a1+2e2,则等于(? )A.4　　B.11　C.3　　D.7

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• [单选题]There is a lot of love in todays world and Im convinced that this is still the most powerful _____ in the world. [ ]A. power B. energy C. force D. strength

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• [单选题]设a＞0且a≠1,命题:函数f(x)=a在R上是增函数 ,命题:函数g(x)=(a-2)x在R上是减函数,则是的( )A.充分不必要条件B.必要不充分条件 C.充分必要条件D.既不充分也不必要条件

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• [计算题]已知点P(2cosα,2sinα)和Q(a,0),O为坐标原点,当α∈(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=-l,设向量与的夹角为θ,求证:cosθ≥.

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• [单选题]命题“若A=B,则sin A=sin B”的逆否命题是( )A.若sinA≠sinB,则4≠BB.若sin A=sin B,则A=BC.若A=B,则sinA≠sinBD.若4≠B,则sinA≠sinB

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• [单选题]Smoking is so harmful to personal health that it kills ________ people each year than automobile accidents.A.seven more timesB.seven times moreC.over seven timesD.seven times

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• [单选题]Mrs. Green always helps her mother even though going to work _________most of her day.A.takes outB.takes downC.takes upD.takes off

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• [计算题]已知点,且原点分的比为,又,求在上的投影.

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• [单选题]You will have to answer_____ your crimes one day. [ ]A. toB. for C. fromD. against

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• [单选题]设向量a,b均为单位向量,且|a+b|=1,则向量a与b的夹角为( )A.3B.—2C.2丌3D.3丌4

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• [单选题]The teacher advises us to use these two course books __________each other.[ ]A. along B. aloneC. alongside D. beside

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• [单选题]I have no idea of what is in fashion nowadays, so my choice might be quite ____.A.abundantB.arbitraryC.considerateD.aggressive

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• [单选题]It has been clearly stated that whoever can solve the problem first shall be entitled ______ the greathonour-Talent of the School. [ ]A. for B. toC. in D. on

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• [单选题]设m、n是不同的直线,α、β、γ是不同的平面,有以下四个命题:①若α∥β、α∥γ,则β∥γ；② 若α⊥β,m∥α,则m⊥β；③ 若m⊥α、m∥β,则α⊥β；④ 若m∥n,nα,则m∥α；其中真命题的序号是[ ]A.①④ B.②③ C.②④ D.①③

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• [单选题]对于平面α和共面的直线m、n,下列命题中真命题是[ ]A.若m⊥α,m⊥n,则n∥αB.若m∥α,n∥α,则m∥nC.若mα,n∥α,则m∥nD.若m、n与α所成的角相等,则m∥n

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• [单选题]非零向量AB与Ac满足ABLACI-BC=0ABI LAC且AB AC IAB LAC 2,则⊿ABC为( )A.三边均不等的三角形B.直角三角形C.等边三角形D.等腰非等边三角形

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• [单选题]____ your performance in physics ____ Jacks and youll realize you should work harder.[ ]A. Compare, withB. Compared, toC. Comparing, withD. Comparing,to

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