I.1 recycle

2 won't dump

3 will be

4 will save

5 will have

6 continues

7 will help

8 travel

9 fine

II.1 studies

2 doesn't hurry

3 will pass

4 will be

5 gives

6 won't pass

7 doesn't stop

8 is

III.1. If teachers teach environmental issues at school, students will be more aware of protecting the environment.

2. If light pollution happens, animals will change their behaviour patterns.

3. If the levels of radioactive pollution decrease, we will switch from nuclear power to renewable energy sources.

4. If the water temperature increases, some aquatic creatures will be unable to reproduces. 

5. If the water is contaminated, people will get more diseases.

IV.1 would look

2 would join

3 would be

4 wouldn't dump

5 would happen

6 were

7 would be

8 had

9 wouldn't be

10 would grow

V.2. If there weren’t so many billboards in our city, people could enjoy the view.

3. If there wasn’t so much light in the city at night, we could see the stars clearly.

4. If we didn’t turn on the heater all the time, we wouldn’t have to pay three million dong for electricity a month

5. If the karaoke bar didn't make so much noise almost every night, the residents wouldn’t complain to its owner

6. She wouldn’t have a headache after work every day if she didn’t work in a noisy office.