Ответ:

1.You musn't throw the rubish in river

2.You must save water

3.You must teach somebody save the nature.

4.You must help janitors

5.You must help animals

6.You musn't do something which is not good for nature.

7.You musn't set a bad example

8..You musn't hunt on animals

9.You have to help keep our pollution clear

10.You must grow tress

11.You musn't throw anything in river

12You must throw batteries in special box

13.You must grow flowers

14.You musn't break trees.

15.You musn't burn grass

16.You must keep your city in purity.

17.You musn't destroy the garden

18.You musn't kill the fishes

19.You musn't smoke

20.You must follow these instructions