我不知道你为什么把$b%4==1 条件

您只需检查$b==1.还有一件事我建议你if and else 二者都所以代码应该是这样的：

 <?php
    $b=1; 
    $args = array(
        \'tax_query\' => array(
            array(
                \'taxonomy\' => \'gens\', 
                \'field\' => \'slug\', 
                \'terms\' => \'newsgen\' 
            )
        ),
        \'post_type\'=>\'\',    //add your post type name 
        \'posts_per_page\' => 4, 
        \'orderby\' => \'asc\', 
    );
        query_posts($args);
        while ( have_posts() ) : the_post(); 
    ?>

    <?php 
        if($b==1) : //change in condition
    ?> 
        <div id="news-big">
        <?php
        $image_url = catch_that_image();
        $image = thumb($image_url, 209, 97);
        ?>
        <a href="<?php the_permalink(); ?>">
        <img src="<?php echo $image[\'url\']; ?>"/></a>
        </div>
    else: //else is added here
        <a href="<?php the_permalink(); ?>"><div class="news-small">
        <div class="container-small">
        <?php
        $image_url = catch_that_image();
        $image = thumb($image_url, 136, 75);
        ?>
        <a href="<?php the_permalink(); ?>">
        <img src="<?php echo $image[\'url\']; ?>"/></a>
        </div>
        <!-- End Thumb Container -->
        </div>
        <!-- End of news-small div -->  
    <?php endif; ?>
    <?php
        $b++;   
        endwhile; 
        wp_reset_query();
?>

我猜你有4条不同的新闻，你想显示第一条新闻使用每个页面的大图像，而大图像的新闻与其他新闻不同，对吗？如果你是对的，下面的代码，可能对你有用

<?php
$b=1; 
$args = array(
    \'tax_query\' => array(
        array(
            \'taxonomy\' => \'gens\', 
            \'field\' => \'slug\', 
            \'terms\' => \'newsgen\' 
        )
    ),
    \'post_type\'=>\'\',    //add your post type name 
    \'posts_per_page\' => 4, 
    \'orderby\' => \'asc\', 
);
    query_posts($args);
    while ( have_posts() ) : the_post(); 
?>

<?php 
if($b==1) : ?> //change here
<div id="news-big">
<?php
$image_url = catch_that_image();
$image = thumb($image_url, 209, 97);
?>
<a href="<?php the_permalink(); ?>">
<img src="<?php echo $image[\'url\']; ?>"/></a>
</div>
<?php else: ?>  //change here
<a href="<?php the_permalink(); ?>"><div class="news-small">
<div class="container-small">
<?php
$image_url = catch_that_image();
$image = thumb($image_url, 136, 75);
?>
<a href="<?php the_permalink(); ?>">
<img src="<?php echo $image[\'url\']; ?>"/></a>
</div>
<!-- End Thumb Container -->

<?php
    endif; //add code
    $b++;   
    endwhile; 
    wp_reset_query();
?>