不确定您实际上是如何显示您的帖子的，无论它是一个自定义查询，还是您在哪个页面执行网格，例如类别页面。这里有一个小片段可能会对您有所帮助。

//get current category page
$category = get_the_category();

//get current category page ID
$category_id = $category->cat_ID;

//set arguments for your desired posts output
$args = array(
\'numberposts\'     => 999,
\'offset\'          => 0,
\'category\'        => $category_id,
\'order\'           => \'DESC\',
\'post_type\'       => \'post\', //if your using a custom post type enter it here
\'post_status\'     => \'publish\' );

$all_posts = get_posts($args);

//get amount of posts
$post_amount = count($all_posts);

//now we know the amount of posts you have in this category, we can do a conditional.

if($post_amount == 1){
//show all your content.
}