––Have you returned the book to the library _______? 

––Yes, I have _________ returned it.

A．yet, yet

B．already, already

C．already, yet

D．yet, already

检查嗜铬细胞宜用（）

A.Bouin液固定

B.Zenker液固定

C.Orth液固定

D.Carnoy液固定

E.Rossman液固定