Multiple values

Hi to all,

I have use this code for an include to show several categories except one :

<!– ———————————–
<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>

<!– If the post is in the category we want to exclude, we simply pass to the next post. –>
<?php if (in_category(‘3’)) continue; ?>

<div class=”post”>

<h2>“><?php the_title(); ?></h2>

<small><?php the_time(‘F jS, Y’); ?></small>

<div class=”entry”>
<?php the_content(); ?>
</div>

<p class=”postmetadata”>Posted in <?php the_category(‘, ‘); ?></p>
</div> <!– closes the first div box –>

<?php endwhile; else: ?>
<p>Sorry, no posts matched your criteria.</p>
<?php endif; ?>
–>

How can i do at line

<!— <?php if (in_category(‘3’)) continue; ?> –>

TO select more than one category (e.g here cat 3 and i would like cat ” & 4 for example.