获取Pages的特色图片 - WordPress

I have a loop that gets the title, content, and link of all pages that are a child of the current page. Everything is working except I don't know how to get the featured image url for these pages so that I can use it as a background image. You can see in the code where I have commented where I am trying to get the url of the featured image.

Here is my code:

<?php
    $mypages = get_pages( array( 'child_of' => $post->ID, 'sort_column' => 'menu_order', 'sort_order' => 'asc' ) );

     foreach( $mypages as $page ) {     
             $content = $page->post_content;
             if ( ! $content ) // Check for empty page
             continue;

             $content = apply_filters( 'the_content', $content );
             $trimmed_content = wp_trim_words( $content, 14, "..." );
             ?>
             <div class="service-box block-grid-item">
                <div class="row">
                   <div class="col-xs-6 col service-image">


             <!-- This is where I am trying to get the featured image url -->


             <?php $feat_image = wp_get_attachment_url( get_post_thumbnail_id($post->ID) ); ?>
                  <a href="<?php echo get_page_link( $page->ID ); ?>" style="background-image: url(<?php echo '$feat_image'; ?>)"</a>
                   </div>
                      <div class="col-xs-6 col service-body">
                        <a href="<?php echo get_page_link( $page->ID ); ?>">
                          <span class="service-title"><?php echo $page->post_title; ?></span>
                          <span class="service-text"><?php echo $trimmed_content; ?></span>
                          <span class="service-link">Read more</span>
                        </a>
                    </div>
                 </div>
             </div>

<?php   }   
?>

You're close, but you should be using wp_get_attachment_image_src(), and should remove the quotes from your variable when you echo the source:

$feat_image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'large' );
<a href="<?php echo get_permalink( $page->ID ); ?>" 
   style="background-image: url(<?php echo $feat_image; ?>)">

You should also take a look at your HTML markup and make sure it's valid.

on above answer some part of code is missing. here is the complete code.

  <?php $feat_image = wp_get_attachment_image_src( get_post_thumbnail_id( 5 ), 'large' );
        print_r($feat_image);
     ?>
    <a href="<?php echo get_permalink( '5' ); ?>" 
       style="background-image: url(<?php echo $feat_image[0]; ?>)"> </a>