— Has ______ problem been solved?    

— Not yet. We're trying to think of ______ way out, but it's quite difficult to find one. [      ]

A. a; the    

B. the; a    

C. a; a      

D. the; the

属于苯烷胺类的药物是：

A．地尔硫卓
B．尼群地平
C．硝苯地平
D．维拉帕米
E．尼莫地平