One tool that is useful during both analysis and design is the ______, which is a pictorial representation of the items of information(entities) within the system and the relationships between these pieces of information.

A．data dictionary

B．dataflow diagram

C．use case diagram

D．entity-relationship diagram

不是由主动脉瓣病变引起主动脉瓣关闭不全的疾病是（）

A.感染性心内膜炎

B.风湿性心脏病

C.先天性二叶主动脉瓣

D.梅毒性主动脉炎

E.主动脉瓣黏液样变性