若Z₁，Z₂为复数，则Z₁²+Z₂²=0是Z₁=0且Z₂=0的（　　）

A．充分非必要条件

B．必要非充分条件

C．充要条件

D．既非充分又非必要条件

— Excuse me, but I wonder if Joan is available at 3:30 this afternoon.

— I'm afraid she _____ Harry Potter and the Philosopher's Stone. [ ]

A. will watch

B. will be watching

C. is to watch

D. is watching