linq to sql 怎么写 select top1 id 的方法

请教高手 linq to sql 如何写 select top1 id 的方法
请帮我把以下方法转成linq 的方法 谢谢啊。。asp.net的

 public static string ReadIdDate()
        {
            StringBuilder texts = new StringBuilder();

            string sql = "select top 1 id from BusinessWaybill order by id desc";

            string source = "Data Source=1.1.1.1;Initial Catalog=testDB;Persist Security Info=True;User ID=sa;Password=***";

            using (SqlConnection conn = new SqlConnection(source))
            {
                SqlCommand com = new SqlCommand(sql, conn);

                conn.Open();

                SqlDataReader r = com.ExecuteReader();
                try
                {
                    while (r.Read())
                    {
                        texts.Append(r.GetInt32(0).ToString());
                    }
                }
                finally
                {
                    r.Close();
                }
            }
            return texts.ToString();
        }
------解决方案--------------------

 DataClasses1DataContext db = new DataClasses1DataContext();
            var s = (from p in db.BusinessWaybill  orderby p.id descending
                    select p.id).First();
     texts.Append(s..ToString());

不知道对不对