Life is like a play; it’s not the length, but the excellence of acting ________ matters.

A．which

B．that

C．who

D．what

用于抗原或抗体的定性、组成和两种抗原相关性分析（）

A.间接凝集试验

B.双向免疫扩散

C.免疫电泳

D.对流免疫电泳试验

E.免疫比浊