$('pl_click').onclick=function(){
	this.blur();
	pls=document.getElementsByClassName('pl');
	eng=document.getElementsByClassName('en');
	for(i=0;i<pls.length;i++){
		Element.show(pls[i]);
		Element.hide(eng[i]);
	}
	Element.addClassName(this,'active');
	Element.removeClassName('en_click','active');
	return false;
}
$('en_click').onclick=function(){
	this.blur();
	pls=document.getElementsByClassName('pl');
	eng=document.getElementsByClassName('en');
	for(i=0;i<pls.length;i++){
		Element.hide(pls[i]);
		Element.show(eng[i]);
	}
	Element.removeClassName('pl_click','active');
	Element.addClassName(this,'active');
	return false;
}