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

to classroom tests. [ ]

A. before

B. since

C. when

D. after

下列哪些行为违反保密规定。（）

A、甲某非法获取、持有国家秘密载体。

B、乙某买卖、转送或者私自销毁国家秘密载体。

C、丙某通过快递等无保密措施的渠道传递国家秘密载体。

D丁某邮寄、托运国家秘密载体出境。