These are helpful after you strip a paragraph for a word limit and want to cut off the last incomplete sentence.
// Remove the last unfinished sentence in a paragraph if it contains $min_word_count or less words
function remove_unfinished_sentence($paragraph, $min_word_count = 3, $replace = '.') {
	$min_word_count = $min_word_count > 1 ? $min_word_count : 1;
	return preg_replace('#(.s*([^s.]+s+){0,'.($min_word_count-1).'}([^s.]+s*))$#ms', $replace, $paragraph);
Of course, if you want to completely remove the last sentence, this will suffice:
// Remove the last sentence in a paragraph
function remove_last_sentence($paragraph, $replace = '.') {
	return preg_replace('#.s*[^.]+$#ms', $replace, $paragraph);
// Output: This is some stuff.
remove_last_sentence('This is some stuff. Blah Blah ');