对于平喘药物的作用，哪项是错误的（）
A.β受体激动
B.稳定肥大细胞膜
C.磷酸二酯酶抑制
D.M受体阻断
E.直接松弛支气管平滑肌
参考答案：E
--- Did you understand what the chairman said at the meeting?
--- No, his meaning didn’t ________. Would you explain it to me?
A．get along
B．get across
C．get back
D．get around
倒闸操作基本条件中对操作设备是如何规定的？
