3.
1 - c
2 - e
3 - b
4 - a
5 - d
4.
1. If we pollute the air, we will have breathing problems
2. If people pollute the water, a lot of fish will die.
3. If we cut down trees in the forest, there will be more floods.
4. If the soil is polluted, plants will die.
5. If there is noise pollution, people and animals will have hearing problems.
5.
1. If you walk to school, you will make the air less polluted.
2. If you use recycled paper, you will save a lot of trees.
3. If the Earth becomes hotter, the plant and animal will die soon.
4. If parents teach their children about the three Rs, they will help environment so much.
5. If you want to save a lot of electricity, don’t use the bulb.
