逆流再生离子交换器压实层树脂的作用是防止()。
参考答案:再生时乱床
This medicine will ____ him of his cough.
A.recover
B.cure
C.treat
D.heal
应放在斗架高层的饮片是()
A.青黛
B.赭石
C.菊花
D.薄荷
E.白梅花