Question

Sharks have lived in the oceans for over 450 million years. There are now about 360 species of sharks, whose size, behavior, and other characteristics differ widely.

Sharks range in size from the 0.1 meter long dwarf-dog shark to the 18-metre long whale shark — the world’s biggest fish. The whale shark, like two other large shark species — the basking shark and the megamouth shark — are harmless to people because they feed on plants and small aquatic animals.

Sharks have extremely sensitive sense organs. Some sharks can detect the scent(气味) of decaying fish or blood even when it is diluted(稀释) to only one part per million parts of seawater. They can probably hear underwater sounds that originate as far as 3 kilometers away and can tell the direction from which underwater sounds are coming.

Sharks are key predators(肉食动物) in the world’s oceans, helping control the numbers of many other ocean predators. Without sharks, the oceans would be overcrowded with dead and dying fish.

Every year, we catch and kill over 100 million sharks, mostly for food and for their fins. Dried shark fins are used to make shark fin soup, which makes a profit for the sellers. Other sharks are killed for sport and out of fear. Sharks are vulnerable to overfishing because it takes most species 10 to 15 years to begin reproducing and they produce only a few offspring.

Influenced by movies and popular novels, most people see sharks as people-eating monsters. This is far from the truth. Every year, a few types of sharks injure about 100 people worldwide and kill about 25. Most attacks are by great white sharks, which often feed on sea lions and other marine mammals. They sometimes mistake human swimmers for their normal prey, especially if they are wearing black wet suits.

If you are a typical ocean-goer, your chances of being killed by an unprovoked(无缘无故的) attack by a shark are about 1 in 100 million. You are more likely to be killed by a pig than by a shark.

Sharks help save human lives. In addition to providing people with food, they are helping us learn how to fight cancer, bacteria and viruses. Sharks are very healthy and have aging processes similar to ours. Their highly effective immune system allows wounds to heal quickly without becoming infected, and their blood is being studied in connection with AIDS research.

Sharks are among the few animals in the world that almost never get cancer and eye cataracts. Understanding why can help us improve human health. Chemicals extracted from shark cartilage(软骨) have killed cancerous tumors in laboratory animals, and these chemicals may someday help prolong our life.

Sharks are needed in the world’s ocean ecosystems. Although they don’t need us, we need them. We are much more dangerous to sharks than they are to us. For every shark that bites a person, we kill one million sharks.

1.Which statement best expresses the main idea of the article?

A. There are many different species of sharks, but only a few of them are dangerous to humans.

B. Sharks are important to the ocean ecosystem and they are a valuable resource for humans.

C. Although some sharks are dangerous to humans, they can help save human lives.

D. Sharks always eat small fishes and they are an essential part of the world’s oceans.

2.Which question is NOT answered in the article?

A. How long does a shark live?

B. How many people are killed by sharks each year?

C. Why are sharks important in medical research?

D. What do humans kill sharks for?

3.It can be inferred from the passage that ______________.

A. movies have given people the wrong impression of sharks

B. most sharks are dangerous to humans

C. sharks will attack anyone who is wearing black

D. it is very likely that ocean-goers will be killed by a shark

Answer 1