The young woman became critically ill and was sent to the big city,where specialists can be called ___to study the ____disease.

A．up , general

B．in, rare

C．on , serious

D．for , important

普萘洛尔降低心肌氧耗量，改善缺血区供血，其主要作用是

A．减弱心肌收缩力

B．β-受体阻断

C．降低血压

D．减慢心率

E．延长舒张期，有利于心肌缺血区血流的改善