— Do you know if it ______ tomorrow?

— Sorry, I don't know. If it ______, we will go fishing. [ ]

A.Will rain, won't rain

B.Will rain, doesn't rain

C.rains, won't rain

D.rains, doesn't rain

硝酸酯类与β受体阻断药联合应用不利于治疗心绞痛的原因是（）。

A.作用机制不同产生协同作用

B.降低血压

C.缩短射血时间

D.消除反射性心率加快

E.降低室壁肌张力