lack release plants level trapped environment liquid average
1. Water is a/an ____that humans and other animals need to live.
2. When the ____of air pollution is very high, cars are not allowed to drive into the city center.
3. As it is now, the ____on Mars is not suitable for human life.
4. The ____temperature of Mars is much lower than Earth's.
5. On Earth, there is fresh water ____in ice.
6. Carbon dioxide is something ____need to make food.
7. Plants ____oxygen into the air, making it possible for humans to breathe.
8. The ____of rain these past few months has made the earth dry.
