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 to 1 people frequently. But these fish² perform a   2 service for earth's waters and for human beings. Yet business and sport fishing³ are threatening their 3 Some sharks are at risk of disappearing from 4

Warm weather may influence both fish and shark activity. Many fish swim near coastal areas 5 their warm waters. Experts say sharks may follow the fish into the same areas, 6 people also swim. In fact, most sharks do not purposely charge at or bite humans. They are thought to mistake a person 7 a 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 the 8 when 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 and 9  produced by animals. These powerful  10 help sharks find their food. Sharks eat fish, any 11 sharks, and plants that live in the ocean.

Medical researchers want to learn more about the shark’s body defense, and immune 12 against disease. Researchers know that sharks 13 quickly from injuries. They study the shark in hopes of finding a way to fight human disease.

Sharks are important for the world’s 14 . They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in ocean waters do not become too 15 . This protects the plants and other forms of life that exist in the oceans.

词汇: purposely / 5p\:pEslI / adv.故意地，蓄意地 immune /i5mju:n / adj.免疫的

charge /tFB:dV / v.（向……）冲（过去） seal /si:l / n. 海豹jewelry /5dVu:ElrI / n.珠宝

注释：

1．It is hard to get people to think of sharks as anything but a deadly enemy：要让人们相信鲨鱼不是（人类的）死敌不是一件容易的事。 anything but意为“决不，远非”，如： His performance in London is anything but a success．（她在伦敦的演出完全不成功。）

2．these fish：这些鱼（指鲨鱼）。 fish单复数同形，如： one fish，two fish，many fish（见第二段第一句）。

3．sport fishing：捕鱼运动。

4．sense of smell：嗅觉

练习:

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   &nbs