&4.程序实现:从键盘输入评委打出的分数,去掉一个最高分和一个最低分,显示平均分。补充空白处代码: static void Main(string[] args) { Score s = new Score(); 1 2 Console.WriteLine("平均分是{0}", 3 ); Console.ReadKey(); } } class Score { ArrayList al = new ArrayList(); public void AddMark() { int i = 0; while (true) { Console.WriteLine("请输入评为分数,以-1结束"); i = int.Parse(Console.ReadLine()); if (i != -1) al.Add(i); else break; } } public void Del() { if (al.Count > 2) { al.Sort(); al.RemoveAt(0); al.RemoveAt(al.Count - 1); } } public double Average() { double sum = 0; foreach (int i in al) { sum += i; } return sum / al.Count; } }