C# LINQ Include

我有一个问题与Include()在实体框架。

我有一些实体

public partial class Travel_RequestEmployee
{
 public virtual Traveler Traveler { get; set; }
}
public abstract partial class Traveler{
}
public partial class Traveler_Employee : Traveler
{
 public virtual Employee Employee { get; set; }
}

我想从Travel_RequestEmployee包含雇员属性。有没有办法让Include()像这样工作?

_context.Travel_RequestEmployee.Include(x => 
x.Traveler.OfType<Traveler_Employee>().Include(e => e.Employee));

请帮帮我?

public partial class Travel_RequestEmployee
{
 public virtual Traveler_Employee Traveler { get; set; }
}