function show_class_stock(form1) {
	var v_type = document.form1.bigclass.value;
	var v_class = document.form1.p_class.length-1;
	var j = classname[v_type].length;
	for(var i=0;i<v_class;i++){
		document.form1.p_class.options[0] = null;
	}
	for(var i=0;i<j;i++){
		document.form1.p_class.options[i] = new Option(classname[v_type][i],classno[v_type][i]);
	}
	return;
 }