Even in fresh water sharks hunt and
kill. The Thresher shark, capable of lifting a small boat out of the water, has
been sighted a mile inland on the Fowey River in Corn-wall. Killer sharks swim
rivers to reach Lake Nicaragua in Central America; they average one human victim
each year. Sewage and garbage attract sharks inland. When floods carry garbage to the rivers they provide a rich diet which sometimes stimulates an epidemic of shark attacks. Warm water generally provides shark food, and a rich diet inflames the shark’s aggression. In British waters sharks usually swim peacefully between ten and twenty miles off- shore where warm water currents fatten mackerel and pilchards for their food. But the shark is terrifyingly unpredictable. One seaman was severely mauled as far north as Wick in Scotland. Small boats have been att A. salt water B. fresh water C. warm water D. deep water 更多"Passage 6 Even in fresh w"的相关试题: [单项选择]Passage 6
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