function KeyDown(){

  if (event.ctrlKey)
      alert ('不得复制！')  //屏蔽 ctrl

}

function Click() {
if (event.button!=1)
	{ alert ('不得复制！');
}}


function oncontextmenu() {

 event.returnValue = false;

 return false;
}


document.onmousedown=Click;
document.onkeydown=KeyDown;
document.oncontextmenu=oncontextmenu;
document.onselectstart=oncontextmenu;
document.ondragstart=oncontextmenu;