2. Some plants can be combined to make the attack power stronger, you can play to the later part of the game to experience it slowly
3. If there is a road that is opened by zombies, put the nuts. If a road is opened by a zombie, put a nut behind the nut, and then put a large mouth flower or pea (since you have played to the second level, you should know that the nut is very effective in defending against zombies)
4. You can also download cheats and pass archives, of course, so that the game is no fun