function clearInp(o){
 var Msg="ÇëÊäÈë²éѯµÄ¹Ø¼ü×Ö!";
 if (o.className.indexOf("doClear")==-1){
 o.className+=" doClear";
 Msg=o.value;
 o.value="";
 }
 o.onblur=function(){
 if (o.value=="") {
 o.value=Msg; 
 o.className=o.className.replace(" doClear","");
 }
 }
}