giúp gấp với ạaaaaaaaaaaa 16. The teacher spoke ______________________(slow) enough for us to understand. 17. She answered all the questions ______________________(good) than the other students and she got a very good mark. 18. This street is too _____________________(crowd). Couldn’t you drive a bit _____________________(slow)? 19. ____________________(Poison) chemical waste should be treated before being dumped into rivers and lakes. 20. Do you think we need to preserve our ancestors’ ______________________(tradition)?