code: public function isQuestion($string)
      {
          $probability = 0;
  
          if (strpos($string, '?')) {
              $probability += 1;
          }
  
          $words = $this->getWords($string);
  
          foreach ($this->inquiryWords as $queryWord) {
              if (!strncmp(strtolower($string), $queryWord, strlen($queryWord))) {
                  $probability += 1;
              } elseif (stristr(strtolower($string), $queryWord)) {
                  $probability += 0.5;
              }
          }
  
          if ($probability >= 2) {
              return true;
          }
  
          return false;
      }
docs: Check if string is question.
  
  @param string $string
  
  @return bool