有关异步搜索的有关问题

  class weatherForcast
        {
            private WeatherWSSoapClient client;
            private string cityName;
            private string weatherResult;
            public weatherForcast(string cn)
            {
                client = new WeatherWSSoapClient();
                client.getWeatherCompleted += new EventHandler<getWeatherCompletedEventArgs>(client_getWeatherCompleted);
                cityName = cn;
                weatherResult = "";
            }

            public string getWeather()
            {
               
                client.getWeatherAsync(cityName, "");
                return weatherResult;
            }

            public void client_getWeatherCompleted(object sender, getWeatherCompletedEventArgs e)
            {

                string[] result = e.Result;
                if (result.Length < 1)
                {
                    weatherResult = "没有此地的天气信息";
                }
                else
                {
                    StringBuilder sb = new StringBuilder();
                    sb.Append(result[1] + "\n");//城市名字
                    sb.Append(result[4] + "\n");//今日天气实况
                    sb.Append(result[5] + "\n\n");//空气质量、紫外线强度

                    sb.Append("今天" + result[7] + "\n");//日期、天气状况
                    sb.Append(result[8] + "\n");//气温
                    sb.Append(result[9] + "\n\n");//风向、风速

                    //sb.Append("明天" + result[12] + "\n");
                    //sb.Append(result[13] + "\n");
                    //sb.Append(result[14] + "\n\n");

                    //sb.Append("后天" + result[17] + "\n");
                    //sb.Append(result[18] + "\n");
                    //sb.Append(result[19] + "\n\n");
                    weatherResult = sb.ToString();

                }
            }
        }

 weatherForcast wf = new weatherForcast("武汉");
string weather = wf.getWeather();