McContax

OK thanks I understand now

OK.Now we are using this function ‘apply_filters’
apply_filters( 'twentyeleven_author_bio_avatar_size', 60 )

And I thought it should be a function ‘add_filter’ in ‘function.php’.
something like add_filter( 'twentyeleven_author_bio_avatar_size', 'example_callback');

I got to admit that I was too tired last night,which makes me unable to explain it cliearly.But thanks for your help.I have solved it.

This code is the one that will show up when I click “TAB”.It’s from theme twentyeleven.

<div class="skip-link"><a class="assistive-text" href="#content"><?php _e( 'Skip to primary content', 'twentyeleven' ); ?></a></div>
<div class="skip-link"><a class="assistive-text" href="#secondary"><?php _e( 'Skip to secondary content', 'twentyeleven' ); ?></a></div>

But thanks for your help I have understood now.

Ok.I have solve this problem.It’s because of the seLinux.When I disable it everything runs well.