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 (. 2. right now, roberto is in the er. he ( for a bad burn on his hand and arm. 3.the game (win, 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 ( it, including my friend, who ( by the police. 5.in my country ( certain prices, such as the price of medical supplies, ( by the government. other prices ( by how much consumers are willing to pay for a product. 6.yesterday, a purse-snatcher ( by a dog. while the thief ( by the police, he ( over a fence into someone's yard, where he encountered a ferocious dog. the dog ( the thief from escaping. 7.the first fish ( on earth about 500 million years ago. up to now, more than 20, 000 kinds of fish (name) ( by scientists. new species (discover) year, so the total increases continually. 8.richard anderson is a former astronaut. several years ago, when he was 52, anderson ( by his superior at an aircraft corporation that he could no longer be a test pilot. he ( 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 ( to extreme cold. it most frequently ( the skin of the cheeks, chin, ears, fingers, nose, and toes. 10.in 1877, a network of lines ( on the surface of mars by an italian astronomer, giovanni schiaparelli. the astronomer ( these lines 'channels, ' but when the italian word (translate) english, it became 'canals.' as a result, some people thought the lines were waterways that ( by some unknown creatures. we now know that the lines are not really canals. canals (exist, on mars. 11.carl gauss ( as a mathematical genius when he was ten. one day, a professor (give) an arithmetic problem. carl ( to add up all the numbers from 1 to 100 (1 + 2 + 3 + 4 + 5 +100 it ( 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) each pair of numbers 1 plus 100, 2 plus 99, 3 plus 98, and so on to 50 plus 51 equaled 101. therefore, he ( 50 by 101, and ( with the answer: 5, 050. 12.captain cook, a british navigator, ( the first european to reach australia's east coast. while his ship ( off australia, his sailors (bring) strange animal on board. cook wanted to know the name of this unusual creature, so he ( his men ashore to ask the native inhabitants. when the natives ( in impromptu sign language to name the animal, they said, "kangaroo." of course, the sailors ( that 'kangaroo' was the animal's name. years later, the truth (discover) 'kangaroo' means 'what did you say? ' however, today the anilmal (call, a kangaroo in english.