<?
$str='knas d asdn lasndlk asldkasdak ?da asdasdasdasdsa.asdgö öm asd as dasd';
function ayir($str, $begin){
	$str2=substr($str, $begin);
	preg_match('~^[\w ]+\W+~', $str2, $out);
	return substr($str, 0, $begin).$out[0];
}
echo ayir($str, 20);
?>