$re = '/(?:^\w+\s)|(\d\?\(\w+\)\s)|(?:\d+\?$)/m';
$str = '3A 4?(1) 5?(2) 6?(a) 7?(4) 8?(a) 9?(ii) 10?';
preg_match_all($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