如何利用API函数SendMessage发送组合键


        public void SendMessage(IntPtr hWnd,KeyboardEvents events,byte key)
        {
            int v = 1;
            int msg = 0;
            if (events == KeyboardEvents.KeyDown)
            {
                int t = (int)MapVirtualKey(key, 0);
                t = t << 16;
                v = v | t;
                t = 010;
                t = t << 29;
                v = v | t;
                //
                msg = WM_KEYDOWN;
            }
            else if (events == KeyboardEvents.KeyUp)
            {
                int t = (int)MapVirtualKey(key, 0);
                t = t << 16;
                v = v | t;
                t = 111;
                t = t << 29;
                v = v | t;
                //
                msg = WM_KEYUP;
            }
            SendMessage(hWnd,(uint)msg, key, v);
        }
上面代码是发送按键消息的函数                            if (ctrl)
                            {
                                SendMessage(_Form.Handle, KeyboardEvents.KeyDown, (byte)Keys.ControlKey);
                            }
                            if (alt)
                            {
                                SendMessage(_Form.Handle, KeyboardEvents.KeyDown, (byte)Keys.Menu);
                            }
                            SendMessage(_Form.Handle, KeyboardEvents.KeyDown,key);
上面是发送按键消息，但是组合键无法实现，请问如何实现，在线等。