4. Fill in the appropriate word from the list. 1. natural…. 2. industrial…. 3. harmful…. 4. oxygen…. 5. rare…. 6. ozone…. 7. ecological…. 8. acid…. 9. air…. 10. dead…. 11. beautiful….. substances, species, riches, security, fish, layer, rain, enterprises, balance, pollution, forests
1 riches , 2 enterprise 3 substances 4 security 5 species 6 layer 7 balance 8 rain 9 pollution 10 fish 11 forests