People have known since ancient times that aspirin（阿司匹林） reduces pain and lowers high body temperature. But that is not all the drug can do. In recent years, it has been used in other ways, too. Small amounts may help prevent a stroke or heart attack. One recent study showed that some people who took two aspirin pills a day had lower rates of colorectal cancer. And, some researchers say aspirin may help patients with colon cancer live longer. So, how did aspirin become so important? The story begins with a willow（柳树）．
2, 000 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. In the 1800s, researchers discovered how to make salicylic acid from the chemical. 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 medicine that Bayer called aspirin. The "a" came from acetyl. The "spir" came from the spirea plant, which also produces salicin. And the "in" ? 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 prevents the body from making the natural substances called prostaglandins. Prostaglandins have several effects on the body. Some cause pain and swelling（肿）． Prostaglandins also make the heart, kidneys(肾) and blood vessels work well. So there is a problem. Aspirin works against all prostaglandins, good and bad. It can also harm the inside of the stomach, and sometimes it can cause bleeding.
But a British study released in 2009 suggested that taking another drug with a small amount of aspirin may help reduce the risk of bleeding. If this proves true, it would help thousands of people who are seeking to prevent life-threatening conditions.
The writer wrote this passage to______.

A．tell us the harm of aspirin

B．help us know aspirin better

C．explain why aspirin is useful

D．prove that aspirin is a good medicine

What do we learn about aspirin from Paragraph 1?

A．It is not used until recent years.

B．Using it for a long time may lead to cancer.

C．It is very dangerous if it is used in the wrong way,

D．It has gained important new uses in recent years.

When was the acetyl salicylic acid created?

A．about 2,000 years ago.	B．In the early 1800s.
C．In the late 1800s	D．In recent years

What is waiting to be solved according to the last paragraph?

A．The bleeding caused by taking aspirin.

B．How to reduce the risk of getting colorectal cancer.

C．How to help patients with colon cancer live longer

D．The problem of low body temperature caused by taking aspirin