A、They are not as dangerous as people think. B、They can be as friendly to humans as dogs. C、They attack human beings by nature.

To most of us, sharks are the most dangerous fish in the sea and they attack humans. However, ac cording to Doctor Clark, who has studied the behavior of sharks for twelve years, humans are not normally on a sharkls menu. What do sharks feed on? Mainly fish and other small sea animals. Doctor Clark also found that sharks don’t eat as much food as people think. For instance, a nineffoot shark only needs two pounds of food a day to keep healthy. But she says sometimes sharks starve and at other times they fill themselves with what they have killed. Around the world, there are only about 100 shark attacks on humans each year, ten of which prove fatal. But consider this: in the U. S. alone, about 3 million people are bitten by dogs each year. Of these, 13 people die, lf a shark bites you says Doctor Clark, the reason is usually because it mistakes you for its natural food. For example, say you went underwater fishing and saw a shark, you could be in trouble. The shark might go for the injured fish you had at tacked and take a big bite of you at the same time. lf you go into a sharkls territory and threaten it, it might try to bite you. That’s because sharks are territorial and tend to guard their territory. Like dogs, they protect the area that they think is their own.
Questions 23 to 25 are based on the passage you have just heard.
23. What does the passage say about the eating behavior of sharks?
24. When might a shark attack humans?
25. What do we learn from the passage about sharks?