12. What is the stomach?
13. What does its lining do?
14. What do the stomach and the gastric juice do to the food we have eaten?
15. How did anybody find out what the stomach could do?
16. Why must all the food we eat be changed?
17. Why do you need food?
18. Why do people who are not growing need food?
19. What does alcohol do to the gastric juice? to the stomach?
20. What is the use of the saliva?
21. How does the habit of spitting injure a person?