含钴饲料以（）生物学效价最高。
A、醋酸钴
B、硫酸钴
C、碳酸钴
D、氧化钴
参考答案：C
--- So what is the procedure?
--- All the applicants before a final decision is made by the authority.
A．interview
B．are interviewing
C．are interviewed
D．are being interviewed
