听力原文： To most of us sharks are the most dangerous fish in the sea and they attack humans. However, according m Doctor Clark, who has studied the behavior. of sharks for twelve years, humans are not normally on the shark's menu. What do sharks feed on, mainly fish and other sea animals? Doctor Clark also found that sharks don't eat as much food as people think. For instance, a ninefoot shark only needs two pound of feed a day to keep healthy. But she says, sharks sometimes starve and at other times they fill themselves with what they have killed. Around the world, there are only about one hundred shark attacks on humans each year, ten of which proved fatal. But consider this, in the US alone, about three million people are bitten by dogs each year. Of thee, thirty people die. If a shark bites you, says Doctor Clark, the reason is usually because it mistakes you for natural. food. For example, say you went underwaterfishing and saw a shark, you could be in trouble. The shark might go for the injured fish you had attacked and take a big bite of you at the same time. If you go into a shark's 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 they think is their own. (26)