$re = '/(\S.*? [a-z]+[.?!])(?=\s+|$)/m';
$str = 'Bill attended the meeting and provide some valuable input. John was at the meeting but said nothing. Mr. Smith cound not attend. A. B. Butler presented the financial results and took questions. ';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php