public static function buildCondition($content, $condition = 'if IE', $operator = 'OR', $global = false)
    {
        if (empty($condition)) {
            return $content;
        }
        $condition_str = '';
        if (is_array($condition)) {
            $count=0;
            foreach ($condition as $_cond) {
                if ($count===0) {
                    $condition_str .= sprintf(self::$conditional_item, 
                        self::parseSingleCondition($_cond));
                } else {
                    $condition_str .= self::parseSingleCondition($operator.$_cond);
                }
                $count++;
            }
        } else {
            $condition_str = self::parseSingleCondition($condition);
        }
        return self::writeCondition($content, 'if ' . $condition_str, $global);
    }