Sharks Perform a Service for Earth's Waters

　　It is hard to get people to think of sharks as anything but a deadly enemy1. They are thought to1people frequently. But these fish2 perform a2service for earth's waters and for human beings. Yet business and sport fishing3 are threatening their3Some sharks are at risk of disappearing from　 4

　　Warm weather may influence both fish and shark activity. Many fish swim near coastal areas5their warm waters. Experts say sharks may follow the fish into the same areas,　 6people also swim. In fact, most sharks do not purposely charge at or bite humans. They are thought to mistake a person7a sea animal, such as a seal or sea lion. That is why people should not swim in the ocean when the sun goes down or comes up. Those are the8when sharks are looking for food. Experts also say that bright colors and shiny jewelry may cause sharks to attack.

　　A shark has an extremely good sense of smell4' It can find small amounts of substances in water, such as blood, body liquids and9produced by animals. These powerful10help sharks fred their food. Sharks eat fish, any11　 sharks, and plants that live in the ocean.

　　Medical researchers want to learn more about the shark's body defense, and immune12against disease. Researchers know that sharks13quickly from injuries. They　study the shark in hopes of finding a way to fight human disease.

　　Sharks are important for the world's14They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in ocean waters do not become too15This protects the plants and other forms of life that exist in the oceans.

　　詞匯:

　　purposely adv.故意地，蓄意地 　immune adj.免疫的

　　charge v.(向……)沖(過去) jewelry n.珠寶

　　seal n. 海豹

　　注釋：

　　1.It is hard to get people tO think of sharks as anything but a deadly enemy：要讓人們相信鯊魚不是(人類的)死敵不是一件容易的事。anything but意為“決不，遠(yuǎn)非”，如：His performance in London is anything but a success.(她在倫敦的演出完全不成功。)

　　2.these fish：這些魚(指鯊魚)。fish單復(fù)數(shù)同形，如：0ne fish，two fish，many fish(見第二段第一句)。

　　3.sport fishin9：捕魚運(yùn)動。

　　4.sense of smell：嗅覺

　　練習(xí):

　　1. A attack　 B meet　 　C love　 D visit

　　2. A terrible B eatable　 　C valuable　 D possible

　　3. A source 　B existence　 C friends D fish

　　4. A Space 　 B Sky　 　C Land　 D Earth

　　5. A because 　B since　 C because of D by reason that

　　6. A whose 　 B which 　C that　 D where

　　7. A to 　B for　 　C like　 D with

　　8. A times 　 B places C seas　 D oceans

　　9. A sciences B mathematics　 　C chemicals D physics

　　10. A feelings B senses C touches　 D tastes

　　11. A those 　B these　 C another D other

　　12. A systems B processes 　C ideas　 D circles

　　13. A recover B reform　 　 C return D rely

　　14. A rivers　 B oceans 　C forests　 D mountains

　　15. A weak　 　B little　 C few D great