— Why have you come to work on foot today?

— Well, my bike ______ and I hate taking a crowded bus.

A. has been repaired

B. is repairing

C. will be repaired

D. is being repaired

下列几种存储器中，存取周期最短的是（）。

A.内存储器

B.光盘存储器

C.硬盘存储器

D.软盘存储器