题目内容：

There is nothing better than having a good scratch when an itch (痒) strikes. But how does scratching stop an itch?

According to a study published in the journal Nature by the scientists from the University of Minnesota, US, the relief you feel does not come from your skin, but from inside our spinal cord (脊柱).

The scientists injected a kind of chemical called histamine(组胺)into a monkey’s legs to produce an itch. The activity in part of the monkey’s spinal cord started to become very strong in response. The scientists then scratched the itchy legs and found that the activity in the spinal cord quickly weakened.

The sudden change in the activity happened because scratching blocked that part of the monkey’s spinal cord. As a result, it could no longer send signals to the brain telling it about the itchy feeling. This is why scratching makes mosquito bites feel better at least temporarily.

“It’s a very important study for itching is a major problem for millions of patients,” said Gil Yosipovitch, PhD, founder of the International Forum for the Study of Itch.

Around 50 different diseases can cause serious itching, including AIDS and kidney diseases.

Scratching might make things more comfortable for small, ordinary itches, but for people with more serious diseases, it can make matters worse. Sometimes an itch can be s0 strong that it keeps the sufferers awake at night, throwing them into a terrible emotional disturbance. Scratching hard can lead to serious skin damage or infection.

The next step for scientists is to discover exactly how itches are reduced when spinal cord signals are stopped. This could help them develop medicines that act in the same way to reduce itching. Patients suffering from serious itching will finally be freed from their misery without tearing up their skin, according to Glenn Giesler, leader of the research.

1.What is the key to determining the feeling of an itch?

A. The skin.

B. The brain.

C. The spinal cord.

D. The bitten tissue.

2.Which is the correct order to show how the experiment was done?

a. The monkey began to have a feeling of itches.

b. The monkey became sensitive to the chemicals.

c. The scientists scratched the itchy legs of the monkey.

d. Scratching made the brain unable to get signals from the spinal cord.

e. To make itches, an injection of histamine was given to the monkey’s legs.

A. e-c-b-d-a

B. e-b-a-c-d

C. d-c-b-e-a

D. b-a-e-d-c

3.What can be inferred from the passage?

A. The cause of itches has not been found yet.

B. All the itches can be got rid of by scratching.

C. Some patients stay awake because of severe itches.

D. Serious itching and scratching can affect people physically and mentally.

4.What may scientists do next according to the passage?

A. They will wipe out itches forever

B. They will announce the findings to the world.

C. They will treat the itch sufferers in a traditional way.

D. They will develop a kind of medicine to relieve itches.