III. Complete the following sentences with the correct form of the words in parentheses: 

1. don't be worry

2. complaint ( complaint letters : thư than phiền )

3. deforestation ( phá rừng )

4. unpolluted ( sạch / k bị ô nhiễm )

6. death ( cái chết )

5. clearly ( see -> adv )

7. suggestion ( make + N + on )

8. disappointed ( be disappointed that )

9. politely ( end -> adv )

10. conservationist ( người ủng hộ việc bảo vệ môi trường )

11. refreshment ( their + N )

12. preservation ( the + N + of )