class ForeachApp{    public static void Main()    {        // 把环境变量中所有的值取出来，放到变量environment中        IDictionary environment = Environment.GetEnvironmentVariables();                // 打印表头        Console.WriteLine("环境变量名\t=\t环境变量值");        // 遍历environment中所有键值        foreach (string environmentKey in environment.Keys)        {            // 打印出所有环境变量的名称和值            Console.WriteLine("{0}\t=\t{1}", environmentKey, environment[environmentKey].ToString());        }    }}