<!-- Hello world! -->

> <!-- Hello
> world! -->

> X <!-- Hello
> world! -->

> <!-- Hello
> world! --> X

> <!-- Hello
world! -->

............................................................
<!-- Hello world! -->
<blockquote>
<!-- Hello
 world! -->
<p>X <!-- Hello
 world! --></p>
<p><!-- Hello
 world! --> X</p>
<!-- Hello
world! -->
</blockquote>
