Restsharp add parameter ยังไง ส่งแบบ get ใน C# เราทำยังไง งง

            string start = "2016-01-30";
            string end = "2016-02-01";

            var client = new RestClient("http://as.com");
            var request = new RestRequest("/coming?datest=" + start + "&dateen=" + end, Method.GET);

            request.AddParameter("datest", start, ParameterType.UrlSegment);
            request.AddParameter("dateend", end, ParameterType.UrlSegment);

            request.RequestFormat = DataFormat.Json;
            //   request.AddBody(obj2Post);
            IRestResponse response = client.Execute(request);
            var content = response.Content;
            Console.WriteLine(content.ToString());