A:奥斯特发现了点电荷的相互作用规律
B:库仑发现了电流的磁效应
C:安培发现了磁场对运动电荷的作用规律
D:法拉第最早引入电场的概念,并发现了磁场产生电流的条件和规律
The football fans often make a ________about which team will win the coming match.
The _______ class is at nine o'clock.
____ ____