— They say Tom's brother is a billionaire.

— _______? He wouldn't accept any help from his brother, even though it was offered. [ ]

A. What if

B. What for

C. So what

D. Forget it

心房收缩期在心血管生理上的意义（）。

A.心房的血液因心房收缩，最终全部被充盈到左心室

B.左心房收缩引起左心室收缩

C.心房收缩期引起心室的快速充盈

D.心房收缩是舒张期的开始

E.心房收缩期是左心室射血的终结