Choose the correct active or passive form of the verb. Be sure the verb is in the correct tense.

1. Friction (reduce) by the application of oil.
2. X-rays (discover) by Roentgen in 1895.
3. The light that you see here shows that the laser beam (reflect) from the moon back to the earth in this moment.
4. Physicists (recently find) traces of the subatomic particle known as «W».
5. The ejection of volcanic duct into the atmosphere (slightly lower) global temperatures in the next few years.
6. A microscope (usually compose) of an objective, a specimen stage, and a light source.
7. Electronic engineers (currently investigate) the feasibility of three dimensional television.
8. Thanks to satellite photographs, the earth’s aurora (show) to be nearly round.
9. Gravity (keep) the Moon in orbit.
10. Floods (ruin) the crops.
11. The colour of solution (change) by adding acid.
12. Nuclear power (generate) electrical energy.
13. Flood control (project) valley residents.
14. Speetroscopy (indicate) the elements in a star.