----- There must be a dozen pens in this house but I can never find one when I need one.   ---- Keep looking. ____is sure to turn up.

A．One

B．It

C．That

D．This

利福平+乙胺丁醇( )。

A．抗菌谱扩大
B．增强杀菌作用
C．增强降压药的效果
D．降低毒性
E．延缓耐药性