不符合药品销售服务礼仪规范基本要求的做法是（）。
A.热情服务
B.尊重顾客
C.热情推荐
D.文明经商
参考答案：C
The old man often advised the young workers on _________the machine and they learned quickly. [ ]
A. to operate
B. how operate
C. how operating
D. how to operate
“冷链”是如何定义？
