1.async await

private void Form2_Load(object sender, EventArgs e)        {            Console.WriteLine("main:"+Thread.CurrentThread.ManagedThreadId);            DoSth();  //不加await不等待DoSth执行完成直接弹出form2_load            MessageBox.Show("form2_load");                  }        async Task DoSth()        {            Do1(); //不加await不等待Do1执行完毕(先弹出 DoSth executed after 3 后弹出 do1 after 5s)相当于并发,加了await就会等待Do1执行完再执行后续相当于阻塞            await Task.Delay(3000);   //这里不能用Thread.Sleep代替 原因见结尾处红色处文字(如果不开线程则Thread.sleep会阻塞住主线程)            Console.WriteLine("dosth:"+Thread.CurrentThread.ManagedThreadId);            MessageBox.Show("DoSth executed after 3s");        }        async Task Do1()        {            await Task.Delay(5000);            Console.WriteLine("do1:"+Thread.CurrentThread.ManagedThreadId);            MessageBox.Show("do1 after 5s");        }