--- Why was Mr. Li so happy this morning?

--- Because he was honoured with a(n) _____ for excellence in teaching.

A．present

B．gift

C．award

D．reward

石蜡包埋组织处理时，透明剂的作用是（）

A.将组织内的固定剂置换出来

B.去除组织内的钙盐

C.去除细胞内的沉淀物

D.将组织内的水分置换出来

E.可以置换乙醇溶解石蜡