protected function display_advanced_search_form() {
        print_collapsible_region_start('', 'advancedsearch', get_string('advancedsearchoptions', 'question'),
                                               'question_bank_advanced_search');
        foreach ($this->searchconditions as $searchcondition) {
            echo $searchcondition->display_options_adv($this);
        }
        print_collapsible_region_end();
    }