Combine the sentences using relative clauses.

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
1. Plastic takes hundreds of years to decompose in the ground. This explains why it is harmful to the environment.
=> Plastic takes hundreds of years to decompose in the ground, .
2. Public transport does not pollute the air as much as private vehicles. That's why more people should consider using it.
=> Public transport does not pollute the air as much as private vehicles, .
3. All students work very hard to help clean up the school. The teacher encourages this.
=> All students work very hard to help clean up the school, .