Choose the correct answer.

1. I don't think people should be allowed to perform experiments ________ animals.

2. There was an explosion in technology ________ the beginning of the 20th century.

3. Let's face ________ - we are destroying the environment and we need to do something now.

4. The distance from the Earth to the Sun is, ________ average, about 149 million kilometres.

5. It's amazing that creatures survive ________ the bottom of the ocean.

6. Fox Talbot ________ the first photograph in 1835.

7. Researchers have ________ to the conclusion that your personality is affected by your genes.

8. Do you mind if I just ________ a quick phone call from here?

9. Many lives were saved ________ the introduction of antibiotics.

10. The ________ of the nuclear accident is still unknown.

11. My father works at the university, doing research ________ weather control.

12. The telescope will photograph distant galaxies, ________ an attempt to understand their past.