php simple html dom ,PHP Simple HTML DOM Parser

Now I'm trying to extract all elements surrounded with a -tag inclduing from an exsiting HTML document. This works fine with

foreach($html->find('b') as $q)

echo $q;

How can I achieve to show up only elements surrounded with the ,-tags followed by a ?

Update:

I've used firebug to get the css path for the elements. Now it looks like this:

foreach ($html->find('html body div#wrapper table.desc tbody tr td div span.marked') as $x)

foreach ($x->find('html body div#wrapper table.desc tbody tr td table.split tbody tr td b') as $d)

echo $d;

But it won't work... Any Ideas?

Update:

To clarify my question here a sample tr of the document with starting table and ending table tags.

1	2	3	4
1	element to extract   1 abed   2 ddee   3 xdef   4 abbcc   5 ab   6 e1	marked