Ex. 52. Use passive or active, in any appropriate tense, for the verbs in brackets.

1. The Amazon valley is extremely important to the ecology of the earth. Forty percent of the world’s oxygen (produce) there.

2. The game (win, probably) by the other team tomorrow. They’re a lot better than we are.

3. There was a terrible accident on a busy downtown street yesterday. Dozens of people (see) it, including my friend, who (interview) by the police.

4. In my country, certain prices (control) by the government, such as prices for medical supplies. However, other prices (determine) by how much people are willing to pay for a product.

5. Yesterday the wind (blow) my hat off my head. I had to chase it down the street. I (want, not) to lose it because it’s my favourite hat and it (cost) me a lot.

6. Right now Alex is in the hospital. He (treat) for a bad burn on his hand and arm.

7. Yesterday a purse-snatcher (catch) by a dog. While the thief (chase) by the police, he (jump) over a fence into someone’s yard, where he encountered a ferocious dog. The dog (keep) the thief from escaping.

8. Frostbite may occur when the skin (expose) to extreme cold. It most frequently (affect) the skin of the cheeks, chin, ears, fingers, nose, and toes.

9. The first fish (appear) on the earth about 500 million years ago. Up to now, over 20,000 kinds of fish (name) and (describe) by scientists. New species (discover) every day, so the total increases continually.

10. Proper first aid can save a victim’s life, especially if the victim is bleeding heavily, has stopped breathing, of (poison).

11. The government used to support the school. Today it (support) by private funds as well as by the tuition the students pay.

12. Richard Anderson is a former astronaut. Several years ago, at the age of 52, Anderson (inform) by his superior at the aircraft corporation that he could no longer be a test pilot. He (tell) that he was being relieved from his duties because of his age. Claiming age discrimination, he took the corporation to court.

13. In the early 80’s, photographs of Mars (send) back to earth by unmanned space probes. From these photographs, scientists have been able to make detailed maps of the surface of Mars.

14. A network of lines (discover) on Mars’ surface by an Italian astronomer around the turn of the century. The astronomer (call) these lines” channels”, but when the Italian word (translate) into English, it became “canals”. As a result, some people thought the lines were waterways that (build) by some unknown living creatures. We know that the lines are not really canals. Canals (exist, not) on Mars.