题目内容：

Scientists have discovered a special biological behavior in dolphins（海豚） that could lead to a treatment for late-onset diabetes（晚发的糖尿病） in humans. Studies on dolphins found that healthy dolphins switch into a diabetic-like state overnight when they are not feeding, but return to normal when they eat the following morning.

The extraordinary finding has led scientists to suggest that dolphins have “genetic switch” that allows them to imitate diabetes while they are not feeding for a night, without suffering any ill effect.

If researchers can identify a similar genetic pathway in human, they may be able to develop drugs to effectively switch off diabetes. Some 2.2 million people in Britain have type 2 (or late-onset) diabetes, a figure that is expected to reach 4 million by 2025 as a consequence of rising levels of obesity（肥胖）.

The tissues of people with type 2 diabetes have become resistant to insulin（胰岛素） so they lose the ability to control sugar levels in their blood. The condition can damage the heart, eyes, kidneys（肾脏） and nerves and contribute to 5% of all deaths, according to the World Healthy Organization.

Dolphins appear to imitate diabetes to keep high levels of blood sugar when food is rare. Like humans, dolphins need some sugar in their blood for their brains to function normally. Venn-Watson’s team analyzed 1,000 blood samples（样本） from 52 dolphins while they didn’t eat anything overnight and fed in the morning. At night time, the dolphins’ metabolism（新陈代谢）changed greatly and showed similar characteristics to that seen in people with type 2 diabetes.

“It is our hope that this discovery can lead to new ways to prevent, treat and maybe even cure diabetes in humans,” said Stephanie Venn-Watson, director of clinical research at the National Marine Foundation in San Diego.

1.What’s the main idea of the passage?

A. Humans get some idea of treating diabetes from dolphins.

B. Dolphins can switch into a diabetic-like state overnight.

C. Humans can suffer the same disease as dolphins.

D. Dolphins should be fed regularly to avoid diabetes.

2.The key to applying the finding to curing human diabetes lies in ____________.

A. producing insulin in a larger amount

B. developing drugs from healthy dolphins

C. identifying a similar genetic pathway in human

D. analyzing more blood samples from hungry dolphins

3. Which of the following statements is TRUE according to the passage?

A. Scientists have found a similar genetic switch in humans.

B. More British people will suffer type 2 diabetes due to obesity.

C. 2.2 million people with type 2 diabetes die in Britain every year.

D. Dolphins imitate diabetes to avoid a high blood sugar level.

4.What will happen to dolphins if not fed for a night according to Venn-Watson?

A. Their metabolism breaks down.

B. They become resistant to insulin.

C. Their heart and kidneys are damaged.

D. They keep high levels of blood sugar.