问题 C: C#中的Switch语句

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace 水仙花数1
{
    class Program
    {
        static void Main(string[] args)
        {
            char grade = (char)Console.Read();
            switch(char.ToUpper(grade))
            {
                case ‘A‘:
                    Console.WriteLine("Pass");
                    break;
                case ‘B‘:
                    Console.WriteLine("Pass");
                    break;
                case ‘C‘:
                    Console.WriteLine("Pass");
                    break;
                case ‘D‘:
                    Console.WriteLine("Pass");
                    break;
                case ‘E‘:
                    Console.WriteLine("No Pass");
                    break;
                default:
                    Console.WriteLine("Score Invalid!");
                    break;
            }
        }
    }
}