sentence cut?

Hello I am doing simple search engine. I have a database with saved pages (without html tags). I need to cut a substring from each page which contains specified keyword. It should be a sentence with this keyword. I tried a regular expression but without effect. eregi("([A-Z][.\n]*".$keyword."[^\.][\.])", $page, $result); There could be pages without correct sentences and this case should be resolved too. Please help Thanks Tristan Rybak