yield return返回枚举器

Question

为什么只会有3次输出？
不应该是一直输出吗？因为 while (enumerator.MoveNext())

public class GameMoves2
{
private IEnumerator _cross;
private IEnumerator _circle;

    public GameMoves2()
    {
        _cross = Cross();
        _circle = Circle();
    }

    public IEnumerator Cross()
    {
        Console.WriteLine($"Cross");
        yield return _circle;
    }
    public IEnumerator Circle()
    {
        Console.WriteLine($"Circle");
        yield return _cross;
    }

static void Main(string[] args)
{
var game = new GameMoves2();

        IEnumerator enumerator = game.Cross();

        while (enumerator.MoveNext())
        {
            enumerator = enumerator.Current as IEnumerator;
        }

        Console.Read();
    }

运行结果：
Cross
Circle
Cross

Answer 1

你写的确实是个死循环，但是打印是在调用Cross和Circle的时候才打印，不调用就不打印呀