public static void TraditionalDelegateSyntax()

        {

            List<int> list = new List<int>();

            list.AddRange(new int[] { 1, 5, 10, 20, 33 });

            Predicate<int> callback = new Predicate<int>(IsEvenNumber);//使用传统委托语法调用FindAll 

            List<int> evenNumbers = list.FindAll(callback);

            foreach (int num in evenNumbers)

                Console.Write("{0}\t", num);

            //Output:   10    20      

        }

        // Predicate<>委托的目标     

        static bool IsEvenNumber(int i)

        { return (i % 2) == 0; }