在模板的header.php 里添加如下代码：
<!-- Self referential canonical tag on all pages --><?phpif ( is_front_page() ) {$canonical_url = get_home_url();if ( ! is_main_site() ) { // add trailing slash for subsite home directories$canonical_url = $canonical_url . '/';}} else {$canonical_url = get_permalink();}?><link rel="canonical" href="<?php echo $canonical_url ?>" />
