：https://developer.wordpress.org/reference/functions/is_category/

举例：

is_category();
// When any Category archive page is being displayed.
 
is_category( '9' );
// When the archive page for Category 9 is being displayed.
 
is_category( 'Stinky Cheeses' );
// When the archive page for the Category with Name "Stinky Cheeses" is being displayed.
 
is_category( 'blue-cheese' );
// When the archive page for the Category with Category Slug "blue-cheese" is being displayed.
 
is_category( array( 9, 'blue-cheese', 'Stinky Cheeses' ) );
// Returns true when the category of posts being displayed is either term_ID 9,
// or slug "blue-cheese", or name "Stinky Cheeses".