We（）the seminar sponsored by you in September last year.

A.aware

B.aware of

C.are aware of

D.are aware

单相桥式整电路接入滤波电容后（）

A.二极管导通时间增加

B.负载电压平均值提高

C.外特性变差

D.负载电压的脉动程度降低