Wordpress：如果单个视图中的这篇文章有特定标签不显示帖子缩略图

How can i do this in WordPress loop:
If this post in single view has specific tag (like: video) not show post thumbnail!

I tried this in loop, but this code not working correctly:

<?php if ( is_tag( 'video' ) ) { ?>
       // do nothing
       <?php }else{ ?>
    <div class="single-img">
        <?php if ( has_post_thumbnail() ) {the_post_thumbnail();} ?>
    </div>
<?php } ?>

You should use the has_tag() function:

<?php if ( has_tag( 'video' ) ) { ?>
       // do nothing
<?php }else{ ?>
    <div class="single-img">
        <?php if ( has_post_thumbnail() ) {the_post_thumbnail();} ?>
    </div>
<?php } ?>