使用了笨办法取了两次值，尝试过ManagementOperationObserver的异步调用，结果出现RPC不可用，暂时没有时间解决这个问题，请高手看到此文给予指点，谢谢。

代码如下：           

ConnectionOptions options = new ConnectionOptions();
            options.Username = "administrator";
            options.Password = "*********";

            ManagementScope Conn = new ManagementScope(@"\\XXX.XXX.XXX.XXX\root\cimv2", options);
            Conn.Connect();

            ObjectQuery query = new ObjectQuery("select * from win32_PingStatus where Address = 'www.sina.com.cn'");

            ManagementObjectSearcher mos =
                        new ManagementObjectSearcher(Conn, query);

            ManagementObjectCollection moc = mos.Get();

            Thread.Sleep(1000);

            moc = mos.Get();

            string m = "";

            foreach (ManagementObject mo in moc)
            {
                object obj = mo.Properties["StatusCode"].Value;

                if (obj == null)
                {
                    m = "PING 执行失败。可能是主机未知。";
                }
                else
                {
                    if (obj.ToString().Trim() == "0")
                    {
                        m = "来自 " + mo.Properties["Address"].Value.ToString() + " 的回复, 字节: " +
                            mo.Properties["BufferSize"].Value.ToString() + ", 时间: " + mo.Properties["ResponseTime"].Value.ToString() +
                            ", TTL: " + mo.Properties["ResponseTimeToLive"].Value.ToString();
                        break;
                    }
                }
            }

            Console.WriteLine(m);