Socket和TcpClient怎样才能知道跟对方断开了没有？

while(bools)
            {
                try
                {

                    if(newSocket[i2].Poll(-1,SelectMode.SelectRead))
                    {
                        if(newSocket[i2].Available>0)
                        {
                            byteMessage=new byte[100];
                            newSocket[i2].Receive(byteMessage,SocketFlags.None); 
                            string msg=System.Text.Encoding.Unicode.GetString(byteMessage);
                            send(msg);
                        }
                        else
                        {
                            newSocket[i2].Shutdown(SocketShutdown.Both);
                            newSocket[i2].Close();
                            th1[i2].Abort();
                            return;
                        }
                    }
                }
                catch
                {
                    Thread.Sleep(10);
                    continue;
                }

            }