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There is a place named Shark Bay(鲨鱼湾) in the Western Australia. At least 28 kinds of sharks are swimming through the clear water there—the largest in the world. Especially tiger sharks are common visitors to Shark Bay. They move their 15-foot-long (about 4.5 meters) bodies through the seagrass, sometimes catching huge sea cows for a meal. Although tiger sharks are dangerous to them, they are important to the health of the ocean ecosystem(生态系统). In fact, they can also be our powerful friends in stopping climate change.
It all comes back to the seagrass that moves with the waves in Shark Bay. The seagrass is food for the sea cows. Each eats about 40 kilograms of seagrass a day. By controlling the sea cow populations, tiger sharks in Shark Bay help the seagrass beds grow. A good seagrass bed stores twice as much CO₂ per square mile as forests do on land.
But in the world, the tiger shark populations are becoming smaller, including some populations in Australia. Off Australia's northeast coast of Queensland, it is said that tiger sharks have fallen by at least 71%, largely because of overfishing and bycatch(误捕). A reduction in tiger sharks means more seagrass eaten and less carbon kept in the ocean.
In Shark Bay, the tiger sharks are able to achieve the balance by keeping sea cow populations down, and not all the bay's seagrass is lost. But here comes the question: What if sharks disappeared from the bay? The need to understand how they support their ecosystems becomes even more urgent(紧急的).
(
A.Tiger sharks eat sea cows.
B.The tiger shark is the largest of its kind.
C.A seagrass bed is about 4.5 meters long.
D.Tiger sharks are harmful to the ocean ecosystem.
(
A.Visitors. B.Sea cows. C.Tiger sharks. D.Seagrass beds.
(
A.About 20 kg. B.About 40 kg. C.About 60 kg. D.About 80 kg.
(
A.They are overfishing sea cows.
B.They are moving out of Australia.
C.Their populations are becoming smaller.
D.They have disappeared.
(
A.To give some information about seagrass.
B.To give some information about Australia.
C.To tell us there will be more sea cows in the future.
D.To call on humans to take action to protect tiger sharks.
There is a place named Shark Bay(鲨鱼湾) in the Western Australia. At least 28 kinds of sharks are swimming through the clear water there—the largest in the world. Especially tiger sharks are common visitors to Shark Bay. They move their 15-foot-long (about 4.5 meters) bodies through the seagrass, sometimes catching huge sea cows for a meal. Although tiger sharks are dangerous to them, they are important to the health of the ocean ecosystem(生态系统). In fact, they can also be our powerful friends in stopping climate change.
It all comes back to the seagrass that moves with the waves in Shark Bay. The seagrass is food for the sea cows. Each eats about 40 kilograms of seagrass a day. By controlling the sea cow populations, tiger sharks in Shark Bay help the seagrass beds grow. A good seagrass bed stores twice as much CO₂ per square mile as forests do on land.
But in the world, the tiger shark populations are becoming smaller, including some populations in Australia. Off Australia's northeast coast of Queensland, it is said that tiger sharks have fallen by at least 71%, largely because of overfishing and bycatch(误捕). A reduction in tiger sharks means more seagrass eaten and less carbon kept in the ocean.
In Shark Bay, the tiger sharks are able to achieve the balance by keeping sea cow populations down, and not all the bay's seagrass is lost. But here comes the question: What if sharks disappeared from the bay? The need to understand how they support their ecosystems becomes even more urgent(紧急的).
(
A
)1.Which of the following statements is true according to Paragraph 1?A.Tiger sharks eat sea cows.
B.The tiger shark is the largest of its kind.
C.A seagrass bed is about 4.5 meters long.
D.Tiger sharks are harmful to the ocean ecosystem.
(
C
)2.What does the underlined word "they" refer to?A.Visitors. B.Sea cows. C.Tiger sharks. D.Seagrass beds.
(
D
)3.How much seagrass can two sea cows eat a day?A.About 20 kg. B.About 40 kg. C.About 60 kg. D.About 80 kg.
(
C
)4.What's the situation of tiger sharks?A.They are overfishing sea cows.
B.They are moving out of Australia.
C.Their populations are becoming smaller.
D.They have disappeared.
(
D
)5.What is the writer's purpose of writing this passage?A.To give some information about seagrass.
B.To give some information about Australia.
C.To tell us there will be more sea cows in the future.
D.To call on humans to take action to protect tiger sharks.
答案
1.A 2.C 3.D 4.C 5.D
