The project manager must maintain an effective communication link with the customer's satisfaction with the progress of the project. The project manager maintains this link through（）.

A.periodic project reports, periodic visits to the customer, and telephonic exchanges

B.subordinates, project team members, and the project sponsor

C.one-time reports, weekly reports, and monthly reports

D.the telephone, facsimile, and data transmission

潜伏期是指（）

A.病原体进入机体到死亡的时间

B.病原体进入机体到临床症状出现的时间

C.病原体进入机体到临床症状恢复的时间

D.病原体进入机体到临床症状结束的时间

E.病原体进入机体到最早临床症状出现的时间