且P在线段AB的垂直平分线上,向量,若

7如图,P为△OAB所在平面上一点,,

A            B             C           D2500

6数列满足,则=(   )

5设函数在定义域内连续,则(   )

A2                B3                C4               D5

A        B         C           D

4不等式的解集是(   )

A               B             C          D

3设,且,则=(   )

2若,则=(   )

A30               B31               C32             D33