我想重新定位wp电子商务插件产品页面产品图像的产品缩略图。wp的默认缩略图功能似乎不起作用

add_image_size( \'product-thumbnail\', 225, 225, array( \'center\', \'top\' ) );
add_image_size( \'thumbnail\', 225, 225, array( \'center\', \'top\' ) );
the_post_thumbnail( array(175, 175), FALSE ); 
add_image_size( \'wpsc-product\', 175, 175, array( \'center\', \'top\' ) );
add_theme_support( \'post-thumbnails\' );
 if ( has_post_thumbnail() ) { 
    the_post_thumbnail( \'thumbnail\' ); 
}