Across
- 3. Expansion of _______ and towns.
- 4. By using ______ energy to heat and light homes and offices.
- 5. We should replace normal bulbs with ______ bulbs.
- 6. We should buy _______ efficient household appliances.
Down
- 1. Which layer lies between 20 to 40 km of the atmosphere.
- 2. This gas is produced by rearing cattle.
- 5. We should replace normal fuel with _______ fuel.