public MainPage()        {            InitializeComponent();            method();//注意：如果2个method写在一个方法里面，调用的时候，2个方法走完才会加载数据，这样用户体验很不好            method1();        }        private  async void method()        {            var a = await AsyncCallbac1("http://www.baidu.com");            TbBlock.Text = a;        }          private  async void method1()        {             var b = await AsyncCallbac1("http://www.google.com");            TtBlock.Text = b;          }        private async Task<string> AsyncCallbac1(string url)        {            try            {                var hc = new HttpClient();                var hrm = new HttpRequestMessage(HttpMethod.Post, url);                hc.Timeout = TimeSpan.FromSeconds(3);                string content = await (await hc.SendAsync(hrm)).Content.ReadAsStringAsync();                return content;            }            catch (Exception ex)            {                MessageBox.Show("hello");                return null;            }        }