—How about paying a visit to Mr. Richardson, our former history teacher?

—Good idea. I will e-mail him today so he ___ know ___ to expect us.

A．may,when

B．would, why

C．will, how

D．shall, why

能体现信息系统以数据为中心的设计思想，为了加速应用项目的开发，允许多个应用项目共同使用的数据库是（）数据库。