将数组转换为IEnumerable <T>

假设您有一个Employee这样的基本类：

class Employee { public string Name; public int Years; public string Department; } 然后（在一个单独的类中）我有以下代码片段（我想我理解除了最后一个之外的所有内容）：

我相信以下代码片段会起作用，因为数组初始化器创建了一个Employee对象数组，该对象与分配给其的workforce变量的类型相同。

Employee[] workforceOne = new Employee[] { new Employee() { Name = "David", Years = 0, Department = "software" }, new Employee() { Name = "Dexter", Years = 3, Department = "software" }, new Employee() { Name = "Paul", Years = 4, Department = "software" } }; 然后，我有以下代码片段。我相信这是可行的，因为Employee隐式对象数组是Array（）类的实现，该类实现了IEnumerable。因此，我相信这就是为什么可以将数组分配给IEnumerable的原因？

IEnumerable workforceTwo = new Employee[] { new Employee() { Name = "David", Years = 0, Department = "software" }, new Employee() { Name = "Dexter", Years = 3, Department = "software" }, new Employee() { Name = "Paul", Years = 4, Department = "software" } }; 然后我有这个代码片段：

IEnumerable workforceThree = new Employee[] { new Employee() { Name = "David", Years = 0, Department = "software" }, new Employee() { Name = "Dexter", Years = 3, Department = "software" }, new Employee() { Name = "Paul", Years = 4, Department = "software" } }; 我不确定为什么此代码片段有效？ IEnumerable 继承自IEnumerable（并重写（或重载？）GetEnumerator()方法），但因此我是否不应该需要强制转换才能使上述工作像这样：

//The cast does work but is not required IEnumerable workforceFour = (IEnumerable )new Employee[] { new Employee() { Name = "David", Years = 0, Department = "software" }, new Employee() { Name = "Dexter", Years = 3, Department = "software" }, new Employee() { Name = "Paul", Years = 4, Department = "software" } }; 数组似乎是从类型隐式向下转换的IEnumerable，IEnumerable 但是我一直想，当您需要将类型转换为更具体的类型时，需要显式转换。

也许我在这里缺少我所理解的一些简单信息，但是有人可以帮助我进行有关此方面的理解。

谢谢。 问题来源于stack overflow