He is a key ____________ in the murder so we must protect him from all kinds of danger.

A．witch

B．watcher

C．wizard

D．witness

下列各组药物中，不属于配伍禁忌的是（）

A.白及与川贝

B.藜芦与细辛

C.水银与砒霜

D.大戟与甘草

E.牵牛子与巴豆