属于短效β2受体激动剂的是()
A.特布他林
B.福莫特罗
C.异丙托溴铵
D.噻托溴铵
E.氟替卡松
参考答案:A
Have you any idea ______we can do to help those ______are in great need?
A.how; who
B.what; /
C.whether; that
D.what; who
过量空气系数a=1的称为()可燃混合气