31. good tennis player

32. very hard students

B.

1. we recycle, we will save natural resources

2. you aren't careful, you will fall over the rock

3. he buys recycled products, he can do a part to save the environment 

4. we put garbage into the bins, we will minimize pollution

5. you work too much, you will be tired

6. the petrol prices are raised, I will have to cycle to work

7. you are careless, you will break the vase

8. Chris works hard, he will pass his exams

9. Ellen borrows, she must give it back next week

10. We will get lost our way in the forest if we don't take the map with us

11. you leave me alone, I'll call the teacher

12. you ask me for the car, I won't lend it to you

1,If we recycle,we will  save natural resources.

2,If you aren't careful,you will fall over the rock.

3,If he buys recycle products,he can do a part to save the environment.

4,If you put garbage into the bins ,you will minimize pollution.

5,If you work too much,you will tired