$re = '/(?<!Mr|Mrs|Dr|Jr)(\.+)(\s+(?![a-z])|(?=[A-Z]))/m';
$str = 'Mr. and Mrs. Smith bought cheapsite.com for 1.5 million dollars, i.e. he paid a lot for it. Did he mind? Dr. Adam Jones Jr. thinks he didn\'t. In any case, this isn\'t true... Well, with a probability of .9 it isn\'t.However, this line wont do it. Qr. Test for Website.COM and Labs.ORG looks good.Creatively not working. t and finished. 9 to start';
$subst = "$1\r\n";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
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