-Can he play the guitar?

-_____, and he can play it well.[ ]

A. Yes, he can.

B. No, he can't.

C. Yes, he does.

D. No, he doesn't.

．一个铁球的质量是1．56kg，体积是0．5dm³，这个铁球是空心的还是实心的?如果是空心的，空心体积有多大?(已知_铁=7．8×10 ^3kg／m ³)