A:跟穿过这一闭合电路的磁通量成正比
B:跟穿过这一闭合电路的磁感应强度成正比
C:跟穿过这一闭合电路的磁通量的变化率成正比
D:跟穿过这一闭合电路的磁通量的变化量成正比
—________ you play the piano for us?—Sorry, I can't play the piano, but I can sing for you.