()定则用于判断载流导体在磁场中受力的方向
A.左手
B.右手
参考答案:A
They feed many _________on their farm, and they often eat _________.
A. chickens; chicken B. chicken; chicken C. chickens; chickens
进行典型调查的主要目的在于了解与有关数字相关的生动具体情况。