Drupal有很多问答模块，你可以尝试，

Question/Answer:  https://www.drupal.org/project/question_answer

FAQ Ask: https://www.drupal.org/project/faq_ask

Answers: https://www.drupal.org/project/answers

Topic: https://www.drupal.org/project/topic

Question: https://www.drupal.org/project/question