如果在实践中不使用关系图，那么在ER图上映射关系?

I have the following tables:

我有以下表格:

______________         ___________      ___________
Persons       |        Enquiries  |     Products   |
______________|        ___________|     ___________|
PersonID      |        EnID       |     ProductID  |
FirstName     |        EnDate     |     Product    |
LastName      |        Enquiry    |     Price      |
Email         |        ___________|     ___________|
Etc.          |
______________|
______