题目内容：

Ten minutes of gentle exercise can immediately change how certain parts of the brain communicate and coordinate (协调) with one another and improve memory function, according to an encouraging new study.

The scientists invited 36 people of different ages to the lab and had them sit quietly on a fixed bicycle for 10 minutes or, on a separate visit, pedal the bicycle at a pace so gentle that it barely raised their heart rates. It also was short, lasting for only 10 minutes. Immediately after each session of the sitting or slow pedaling, the people completed a computerized memory test during which they would see a brief picture of, for instance, a tree, followed by a variety of other images and then a new image of either the same tree or a similar one. The people would press buttons to show whether they thought each image was new or the same as an earlier shot. The test is difficult, since many of the images closely resemble one another. It requires rapid, skillful scanning recent memories to decide whether a picture is new or known. Next, the scientists had each people repeat this process--riding or sitting on the bike for 10 minutes and then completing memory testing--but the testing now took place inside an M. R. I. machine(磁共振成像仪)that scanned the people's brains while they responded to the images.

Then the researchers compared results. The effects of the exercise were clear. The people were better at remembering images after they had ridden the bike, especially when the images most closely resembled one another. In other words, the harder their memories had to do their best, the better they performed after the exercise. The M. R. I. scans showed that memory parts of each people's brain lit up at the same time with parts of the brain associated with learning, indicating that these physically separate parts of the brain were better connected now than when the people had not first exercised.

1.How did the researchers conduct the study?

A. By filling up questionnaires.

B. By interviewing many people.

C. By comparing experiment data.

D. By referring to historical reports.

2.Who might benefit most from the study result?

A. The marketers promoting fixed bicycles.

B. The young people crazy about body building.

C. The white collars doing long-term mental work.

D. The blue-collars doing heavy physical labor work.

3.Which of the following statements agrees with the study result?

A. The light exercise is only good for young people.

B. The more the exercise is, the better the brain works.

C. The exercise can coordinate different parts of the body.

D. The exercise has more positive effect when the brain works harder.

4.What can be the best title for the text?

A. Even ten minutes' exercise may be good for the brain

B. There is no need for humans doing exercise every day

C. Only ten minutes' light exercise benefits the young most

D. Exercise can change people's brains and minds in a long time