关于支气管哮喘发作时的下列检查，哪项不正确()

A．X线检查缓解期可无异常

B．中度哮喘时可出现呼吸性碱中毒

C．严重发作时可出现奇脉

D．肺功能异常改变为不可逆性

E．病情越严重，哮鸣音反而减少

—Sorry, I have to ________ now. It's time for class.

—OK, I'll call back later.[ ]

A. hang up  

B. break up

C. give up  

D. hold up