这里我为您编写了一个函数-

function the_dramatist_get_post_by_time_range( $args = \'\' ) {
    $date_query = array();
    if ( $args === \'last 7 days\') {
        $date_query = array(
            \'after\' => \'1 week ago\'
        );
    } else {
        $month_ini = new DateTime("first day of last month");
        $month_end = new DateTime("last day of last month");
        $date_query = array(
            array(
                \'after\' => $month_ini->format(\'Y-m-d\'),
                \'before\' => $month_end->format(\'Y-m-d\'),
            )
        );
    }
    $params = array(
        \'post_type\' => \'attachment\',
        \'post_status\' => \'publish\',
        \'orderby\' => \'date\',
        \'order\' => \'DESC\',
        // Using the date_query to filter posts from last week
        \'date_query\' => $date_query
    );
    return get_posts($params);
}

请先用不同的日期进行测试。如果你发现什么不对劲，请敲门。我认为日期范围可能会导致一些问题。所以请先测试一下。