—What are you supposed to do while chatting with friends on the Internet so that the other person doesn't        ?

—You are supposed to type quickly.[ ]

A. become annoying    

B. feel boring    

C. get bored    

D. get used to it

变化的磁场在导体中产生电动势的现象称为（）。

A、电磁感应

B、感应电动势

C、感应电流

D、磁感应强度