—Why didn’t you help him?

—I __________, but I didn’t have the money.

A．I did have

B．I would have

C．will have

D．must have

在数据库逻辑结构设计中，将E—R模型转换为关系模型应遵循相应原则。对于三个不同实体集和它们之间的一个多对多联系，最少应转换为多少个关系模式

A．2

B．3

C．4

D．5