单项选择题
A.50%B.60%C.70%D.80%
A.进门靠近水帘端B.栏舍中间位置C.远离进门口风机端D.任意位置
A.2m*1m*1mB.2m*2m*1mC.1.8m*1.8m*0.9mD.1.8m*0.9m*0.9m