I. Complete the sentences, using the right form of the word in brackets.
1. They sat around the fire for (warm)
2. (industry) waste can be recycled.
3. Those cars are cheaper because of the (develop) of new technology.
4. Extinct animals did not successfully adapt to (environment) changes.
5. Most houses in the city are heated (electricity).
6. It was impossible to (hot) their food without a fire.
7. I hope you will pass the (enter) examination.
8. At one time, lions lived (through) Africa, Asia, and Europe.
9. He looked (think) when he heard the news.
10. As the car is small, it’s much more (economy) on petrol.

I. Fill in each gap with one word.
1. The sun is the only ...... of solar energy.
2. The .......of that city is two million people