—You can use MSN to talk with Kevin on the Internet.

—I know. But can you tell me _______?[ ]

A. what I can use it

B. how can I use it

C. why can I use it

D. when I can use it

可以作为工程项目风险核对表使用的是( )。

A．风险分解结构的最底层
B．风险分解结构的次底层
C．风险分解结构的最高层
D．风险分解结构的次高层