下列物质中不能用作饲料原料的是（）。
A、皮革蛋白粉
B、沸石粉
C、牛骨粉
D、猪肉骨粉
参考答案：A
—Good morning, Grand hotel
—Good morning, I'd like to book a meeting room for the time from 3p.m. to 6p.m. this afternoon.
— [ ]
A. What can I do for you?
B. Just a minute, please!
C. What's the matter?
D. I don't care.
六效管式降膜蒸发器组最后一效产生的二次蒸汽进入（）。
A、热水封槽
B、预热器
C、闪蒸器
D、水冷器
