The story took place in the 1920s, a time ________ jazz became popular in America.

A．which

B．with which

C．when

D．among which

肝性脑病的发病机制是（）

A.假神经递质

B.氨中毒

C.氨硫醇和短链脂肪酸的协同毒性作用

D.氨基酸代谢不平衡

E.上述多种因素综合作用所致