1.

Use either active or passive, in any appropriate tense for the verbs in parentheses.
1/The Amazon valley is extremely important to the ecology of the earth. Forty percent of the world's oxygen (produce)____there.

2.
Right now, Roberto is in the ER. He (treat)____ for a bad burn on his hand and arm.

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

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

5.In my country (Kuwait?), certain prices, such as the price of medical supplies, (control)___ by the government. Other prices (determine)_____
by how much consumers are willing to pay for a product.

6.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.

7.The first fish (appear)____ on earth about 500 million years ago. Up to now, more than 20,000 kinds of fish (name) ____and (describe)____ by scientists. New species (discover) ______every year, so the total increases continually.

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

9.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.

10.In 1877, a network of lines (discover)_____ on the surface of Mars by an Italian astronomer, Giovanni Schiaparelli. 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 creatures. We now know that the lines are not really canals. Canals (exist, not)____
on Mars.

11.Carl Gauss (recognize)_____ as a mathematical genius when he was ten. One day, a professor (give) _____him an arithmetic problem. Carl (ask)___ to add up all the numbers from 1 to 100 (1 + 2 + 3 + 4 + 5 ... +100). It (take)_____ him only eight seconds to solve the problem. How could he do it so quickly? Can you do it quickly?
Carl Gauss could do it quickly because he (know) _____that each pair of numbers --- 1 plus 100, 2 plus 99, 3 plus 98, and so on to 50 plus 51 --- equaled 101. Therefore, he (multiply)_____ 50 by 101, and (get)____ with the answer: 5,050.

12.Captain Cook, a British navigator, (be)______ the first European to reach Australia's east coast. While his ship (lie)____ off Australia, his sailors (bring) _____a strange animal on board. Cook wanted to know the name of this unusual creature, so he (send)____
his men ashore to ask the native inhabitants. When the natives (ask)_____
in impromptu sign language to name the animal, they said, "Kangaroo." Of course, the sailors (believe)_____ that 'kangaroo' was the animal's name. Years later, the truth (discover) _____. 'Kangaroo' means 'What did you say?' However, today the anilmal (call, still)_____ a kangaroo in English.