—So why didn't you meet us on Saturday then?  

—I'm sorry about that.

—I  _________

—I thought you were meeting next Saturday.[ ]

A. get the fact straight

B. have a good nose for it

C. play a trick of the trade

D. get the wrong end of the stick

设p、q是两个命题，则“复合命题p或q为真，p且q为假”的充要条件是（　　）

A．p、q中至少有一个为真

B．p、q中至少有一个为假

C．p、q中中有且只有一个为真

D．p为真，q为假