—Haven’t you seen the speed limit sign? Please drive     .

—Sorry,but I have to.

A．more slowly a bit

B．slowly a bit more

C．a bit more slowly

D．slowly more a bit

在直流发电机中判断感应电动势E的方向是按（）确定。

A.左手定则

B.电磁定律

C.右手定则

D.楞次定律