Since ancient times, people have known about its ability to reduce pain and high body temperature. More than 2000 years ago, the Greek doctor Hippocrates advised his patients to chew on the bark and leaves of the willow.
The tree contains a chemical called salicin（柳醇）. From salicin, researchers in the 1800s discovered how to make salicylic acid（酸）. And in 1897, a chemist named Felix Hoffmann at Friedrich Bayer and Company in Germany created acetyl salicylic acid. Later it became the active substance in a new medicine that Bayer called aspirin. The "a" came from acetyl. The "spir" came from the spirea plant, which also produces salicin. And the "in" Well, that is a common way to end medicine names.
In 1982, a British scientist shared the Nobel Prize in Medicine in part for discovering how aspirin works. Sir John Vane found that aspirin blocks the body from making natural substances called prostaglandins（前列腺素）.Prostaglandins have several effects on the body. Some cause pain and the expansion, or swelling（ 肿瘤; 膨胀）, of damaged tissue. Others protect the lining of the stomach and small intestine. Prostaglandins also make the heart, kidneys and blood vessels （血管）work well. But there is a problem. Aspirin works against all prostaglandins, good and bad. Scientists learned how aspirin interferes with an enzyme（酶）. One form of this enzyme makes the prostaglandin that causes pain and swelling. Another form of the enzyme creates a protective effect. So aspirin can reduce pain and swelling in damaged tissues. But it can also harm the inside of the stomach and small intestine（肠）.
What sickness can the medicine from the willow deal with according to the passage?

A．Cold

B．Toothache

C．Cancer

D．Skin disease

What can we know about Prostaglandin according to the passage?

A．It results from pain.

B．It prevents the lining of the stomach and small intestine.

C．It causes blood vessels to work wrongly.

D．It is sometimes good but sometimes bad.

What can we know about aspirin according to the passage?

A．Aspirin can treat almost diseases.

B．Aspirin can create the protective enzyme.

C．Aspirin can harm the inside of the stomach and small intestine.

D．Aspirin can protect the inside of the stomach and small intestine.