c# JSON反序列化有关问题

c# JSON反序列化问题
c# 如何读取这个JSON格式的数组啊。。。这种的我能读到，那种的怎么得到啊。。。。求教

        [DataContract]
        public class DanTengObj
        {
            [DataMember(Order = 1, Name = "fruits")]
            public Fruits fruits { get; set; }
            [DataMember(Order = 2, Name = "name")]
            public Name name { get; set; }

            [DataContract]
            public class Fruits
            {
                [DataMember(Order = 1, Name = "a")]
                public string a { get; set; }
                [DataMember(Order = 2, Name = "b")]
                public string b { get; set; }
                [DataMember(Order = 3, Name = "c")]
                public string c { get; set; }
            } 
 

            [DataContract]
            public class Name
            {
                [DataMember(Order = 1, Name = "z")]
                public string z { get; set; }
                [DataMember(Order = 1, Name = "l")]
                public string l { get; set; }
            }
        }

        static void DanTengJsonTest()
        {
            string jsonStr = @"{""fruits"":{""a"":""orange"",""b"":""banana"",""c"":""apple""},""name"":{""z"":""zhangsan"",""l"":""lisi""}}";

            DataContractJsonSerializer js = new DataContractJsonSerializer(typeof(DanTengObj));

            using (MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(jsonStr)))
            {
                DanTengObj obj = js.ReadObject(ms) as DanTengObj;
                Console.WriteLine(obj.fruits.a);
            }
        }