. My pain ___________ obvious the moment I walked into the room, for the first man I met  asked me pitifully:" Are you feeling all right?"

A．must be

B．must have been

C．could be

D．could have been

卫生统计工作的步骤中，最关键的一步是

A．统计设计
B．调查表设计
C．搜集资料
D．整理资料
E．分析资料