$re = '/(?=\()(?:(?=.*?\((?!.*?\1)(.*\)(?!.*\2).*))(?=.*?\)(?!.*?\2)(.*)).)+?.*?(?=\1)[^(]*(?=\2$)/s';
$str = 'Answer ((((((((((misery)))))))))) adieus add wooded how nay men before though. Pretended belonging contented (mrs suffering favourite you the continual). Mrs civil nay least means tried drift. (Natural) (end) (law) whether but and towards certain. (Furnished (unfeeling his sometimes (see day promotion. Quitting) informed concerns) can men now). Projection to or up conviction uncommonly delightful continuing. In appetite ecstatic opinions hastened by handsome admitted.
Answer misery adieus add wooded how nay men before though. Pretended belonging contented (mrs suffering favourite you the continual). Mrs civil nay least means tried drift. (Natural) (end) (law) whether but and towards certain. (Furnished (unfeeling his sometimes (see) day promotion. Quitting) informed concerns) can men now. Projection to or up conviction uncommonly delightful continuing. In appetite ecstatic opinions hastened by handsome (((admitted.
Answer misery))) adieus add wooded how nay men before though. Pretended belonging contented mrs suffering favourite you the continual. Mrs civil nay least means tried drift. (Natural) (end) (law) whether but and towards certain. (Furnished (unfeeling his sometimes (see day promotion. Quitting) informed concerns) can men now). Projection to or up conviction uncommonly delightful continuing. In appetite ecstatic opinions hastened by handsome admitted.';
preg_match_all($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