Ответ:
1. If you eat junk food, you will be fat.
2. If it rains, we will stay at home.
3. I will be happy if my mum buys me a new phone.
4. If I see him, I will tell him about my trip.
5. May I take your book?
6. You have to be good at school if you want to get what you want.
7. I could read when I was six.
8. She might need to work more.
9. Fruits and vegetables are healthy food
10. I do not eat unhealthy food because that's bad for me.
11. Meat, fish, eggs, beans and nuts are also important.
12. Milk products such as milk, cheese and yogurt are necessary because they contain calcium.
Держи :)