1.复数等于                                                                                                          (    )
       A.2i                           B.-2i                          C.2-2i                        D.2+2i
2.已知全集U和集合A,B如图所示,则=                                                     (    )
       A.{5,6}                   
       B.{3,5,6}
       C.{3}                        
       D.{0,4,5,6,7,8}
3.已知两点,向量若,则实数k的值为              (    )
       A.-2                          B.-1                           C.1                            D.2
4.下面给出的四个点中,位于所表示的平面区域内的点是                         (    )
       A.(0,2)                 B.(-2,0)                C.(0,-2)                D.(2,0)
5.已知m,n是两条不同直线,α、β是两个不同平面,下列命题中不正确的是             (    )
       A.若                   B.若
       C.若                       D.若
6.“”是“”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