What channel is general communication used?（）

A.any appropriate channel except public communication

B.any appropriate channel except for public communications

C.any appropriate channel besides public communication

D.any appropriate channel beside public communication

哪种药物是选择性β受体阻滞剂，选择性阻断β¹受体而不阻断β²受体()

A．噻吗心安

B．贝特舒

C．贝他根

D．美开朗

E．派立明