Dictionary<string, string> dic = new Dictionary<string, string>();
            dic.Add("a", "北京");
            dic.Add("c", "上海");
            dic.Add("b", "广州");
            dic.Add("d", "深圳");

            foreach (KeyValuePair<string, string> d in dic)
            {
                Console.WriteLine(d.Key + "  " + d.Value);
            }

            foreach (var itm in dic)
            {
                Console.WriteLine(itm.Key + "  " + itm.Value);
            }

            foreach (string s in dic.Keys)
            {
                Console.WriteLine(s + "  " + dic[s]);
            }

            foreach (string s in dic.Values)
            {
                Console.WriteLine(s);
            }

            字典排序：List<KeyValuePair<string,string>> list = dic.OrderBy(r => r.Key).ToList<KeyValuePair<string, string>>();
　　　　　　　//dic =dic.OrderByDescending(r => r.Key).ToDictionary(r => r.Key, r => r.Value);
            foreach (KeyValuePair<string, string> kv in list)
            {
                Console.WriteLine(kv.Key + "  " + kv.Value);
            }