无法实现接口成员，因为它不是公共的?

Question

怎么在实现IEnumerator接口时，必需加上System.Collections.IEnumerator？
        public IEnumerator GetEnumerator()
        {
            Enumerator enumerator = new Enumerator(0);
            return enumerator;
        }
        public class Enumerator : IEnumerator, IDisposable
        {
            private int state;
            private object current;
            public Enumerator(int state) { this.state = state; }
            //注释掉时出现错误：无法实现接口成员，因为它不是公共的
            bool /*System.Collections.IEnumerator.*/MoveNext()
            {
                switch (state)
                {
                    case 0:
                        current = "Hello ";
                        state = 1;
                        return true;
                    case 1:
                        current = "World !";
                        state = 2;
                        return true;
                    case 2:
                        break;
                }
                return false;
            }
            void System.Collections.IEnumerator.Reset()
            {
                throw new NotSupportedException();
            }
            object System.Collections.IEnumerator.Current
            {
                get
                {
                    return current;
                }
            }
            void IDisposable.Dispose()
            { }
        }
    }
    class program
    {
        static void Main(string[] ags)
        {
            HelloCollection pro = new HelloCollection();
            foreach (var temp in pro)
            {
                Console.WriteLine(temp);
            }
        }
    }

Answer 1

在方法名前加上 public 修饰void System.Collections.IEnumerator.Reset()
to
public void System.Collections.IEnumerator.Reset()

Answer 2

在方法名前加上 public 修饰