The party held last night was _______ success; we sang and danced until it came to _____ end at twelve.

A．/; /

B．a; the

C．the; an

D．a; an

竞争性拮抗药的特点为

A．本身不能产生生理效应

B．本身能产生生理效应

C．与受体结合是可逆的

D．能抑制激动药的最大效应

E．使激动药的量效曲线平行右移