function switchTab(prefix, current, total, activeclass) {
	activeclass = !activeclass ? 'a' : activeclass;
	for(var i = 1; i <= total;i++) {
		var classname = ' '+document.getElementById(prefix + '_' + i).className+' ';
		document.getElementById(prefix + '_' + i).className = classname.replace(' '+activeclass+' ','').substr(1);
		document.getElementById(prefix + '_c_' + i).style.display = 'none';
	}
	document.getElementById(prefix + '_' + current).className = document.getElementById(prefix + '_' + current).className + ' '+activeclass;
	document.getElementById(prefix + '_c_' + current).style.display = '';
}