In my point of view, the question is not _____ the world is going to have a new economic crisis, but when.

A．that

B．how

C．what

D．whether

临床输血浆的主要目的是

A．补充凝血因子

B．补充血容量

C．提供能量

D．增加血红蛋白量

E．补充微量元素