$11.$ If the soil were not badly polluted, the trees and grasses could grow here.

$12.$ If you eat a lot of sweets, you will have problems with your teeth.

$13.$ If the rain is heavy, it will prevent us from going out.

$14.$ If children don't play sport, it will make children feel sleepy and tired.

$15.$ If you don't stop talking, you won't understand the lesson.

$16.$ If you study hard, you will pass your exam easily.

$17.$ If I were you, I wouldn't throw those clothes away.

$18.$ If they get up early, they won't be late for school.

$19.$ If that man worked hard, he could earn money.

$20.$ If I knew the answer, I would tell him.

*Cấu trúc:

- Câu điều kiện loại 1: If + S + V (s/es), S + will + V.

- Câu điều kiện loại 2: If + S + V (Pii), S + would/ could/ might + V.