using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace Ch03Ex02{    class Program    {        static void Main(string[] args)        {            double firstNumber, secondNumber;            string userName;            Console.WriteLine("请输入姓名:");            userName = Console.ReadLine();            Console.WriteLine("请输入第一个数字:");            firstNumber = Convert.ToDouble(Console.ReadLine());            Console.WriteLine("请输入第二个数字:");            secondNumber = Convert.ToDouble(Console.ReadLine());            Console.WriteLine("数字{0}加{1}结果是:{2}",firstNumber,secondNumber,firstNumber+secondNumber);            Console.WriteLine("数字{0}减{1}结果是:{2}", firstNumber, secondNumber, firstNumber - secondNumber);            Console.WriteLine("数字{0}乘{1}结果是:{2}", firstNumber, secondNumber, firstNumber * secondNumber);            Console.WriteLine("数字{0}除{1}结果是:{2}", firstNumber, secondNumber, firstNumber / secondNumber);            Console.WriteLine("数字{0}余{1}结果是:{2}", firstNumber, secondNumber, firstNumber % secondNumber);            Console.ReadKey();        }    }}