通过php调用多个字段

How can I call size and megabyte together? I am using this code, but it dose not work, at all.

<?php if( get_field('size' , 'megabyte'  )):?>
<span class="right">Size: <?php the_field('size' , 'megabyte' );?></span>     
<?php endif; ?>

</div>

    <?php if ( get_field( 'size' ) && get_field( 'megabyte' ) ) { ?>
         <span class="right">Size: <?php the_field('size');?><?php the_field('megabyte');?></span>      
    <?php }?>

The && operator is equivalent to "and".