Doing your homework is a sure way to improve your test scores, and this is especially true ____ it comes

to classroom tests.

 [ ]

A. since

B. before

C. after

D. when

内存按工作原理可以分为（）这几种类型。

A.RAM和BIOS

B.BIOS和ROM

C.CMOS和BIOS

D.ROM和RAM