Wang Haijian, Hubei bombing principal, was shot to death for his leading role in __________ a homemade bomb near a branch of state-owned China Construction Bank in Wuhan on Dec. 1, 2011.

A．set off

B．set aside

C．set down

D．set out

CAI的优点体现在( )。

A．交互性

B．即时反馈

C．以生动形象呈现信息

D．自定步调

E．同步教学