ER图有关问题

ER图问题!高手进
Draw an ER diagram to capture the requirements as stated below:
A Company has several business units. Each business unit has multiple projects.
Employees must be assigned to one business unit. One or more employees are
assigned to a project, but an employee may be on vacation and not assigned to any
projects. One of the assigned employees will be project manager for that project.


------解决方案--------------------
employee/m develop n/project
------解决方案--------------------
有点晕。是employee１..*　------------１　project 吧