降温速度越慢速冻产品的品质保存（）。
A．越好
B．越差
C．不变
参考答案：B
The house could fall down soon if no one ______ some quick repair work.
A. has done
B. is doing
C. does
D. had done
下列哪个是阿片受体的特异性拮抗药
A．美沙酮 B．纳洛酮 C．芬太尼 D．曲马朵 E．烯内吗啡
