A. What are they doing now?
B. Where are they?
C. Do you see any animals?
Amy:____
Mike: Yes, I see two ducks.
Mike: They are in the river
Mike: They're swimming.
连一连。
在社会生活中,不同的角色承担着不同的责任。作为社会成员,我们应该( )
如图所示,闭合的矩形导体线圈abcd在匀强磁场中绕垂直于磁感线的对称轴OO′匀速转动,沿着OO′方向观察,线圈沿逆时针方向转动.已知匀强磁场的磁感强度为B,线圈匝数为n,ab边的边长为l1,ad边的边长为l2,线圈总电阻为R,转动的角速度为ω,则当线圈转至图示位置时( )