治疗脾胃虚寒，脘腹冷痛，兼寒饮伏肺，咳嗽气喘，痰多清稀者，应首选（）
A.附子
B.肉桂
C.干姜
D.细辛
E.高良姜
参考答案：C
在由CO和O2组成的混合气体中，测知碳元素的质量分数为18%，则混合气体中CO和O2的质量比为（ ）
A．2:1
B．1:2
C．29：21
D．21：29
It is required that the students _____ mobile phones in their school, so seldom _____ them using one. [ ]
A. shouldn't be used; will you see
B. not use; will you see
C. don't use ;will you see
D. shan't use; you will see
