1. The fish are dead because of the polluted water.
2. Global warning happens cause there is too much carbon dioxide in the atmosphere.
3. Ships spill oil in oceans and rivers, which leads to the death of many aquatic animals and plants.
4. If teachers didn't teach environmental issues at school, students wouldn't be more aware of protecting the environments. 
5. If she didn't work in a noisy office, she wouldn't have a headache after work everyday. 
6. Vy had a stomachache since she ate a big dinner.
7. If people didn't throw rubbish in the streets, the streets would look attractive.
8. If you were the president, what would you do to help the environment? 
9. The air will be fresh if we plant a lot a of trees.
10. We will save lots of trees if we don't waste paper