可以向协变委托分配同一类型的其他委托，但需使用派生程度较大的泛型类型参数。
A covariant delegate can be assigned another delegate of the same type, but with a more derived generic type parameter.
可以向协变委托分配同一类型的其他委托，但需使用派生程度较大的泛型类型参数。
A covariant delegate can be assigned another delegate of the same type, but with a more derived generic type parameter.
应用推荐