Each of the 400 people received from their boss ____ gift-"Who moved my cheese?"- ____ best-seller in

the US-to understand how to deal with changes in their lives and work. [ ]

A. the; 不填

B. a; a

C. a; 不填

D. the; a

某一化学物质若可以直接配制标准溶液或作为标定标准溶液的物质，不必具备下列哪种条件（）。

A.物质的纯度要高

B.物质的组成要与化学式完全相符

C.性质稳定

D.具有较大的摩尔质量

E.具有氧化还原性质