Question

已知m＞0,设命题甲:两个实数a、b满足|a-b|＜2m,命题乙:两个实数a、b满足|a-1|＜m且|b-1|＜m.则甲是乙的_________________条件.(    )

A.充分不必要                              B.必要不充分

C.充要                                       D.既不充分也不必要

Answer 1

解析：∵|a-b|=|(a-1)-(b-1)|≤|a-1|+|b-1|＜m+m=2m,

∴由乙能推出甲,反之则不能.故选B.

答案:B