A、The left side. B、The right side. C、The frontal part. D、The back part. C短文中提到研究人员通过要求受测试人员完成不同的任务，记录下大脑的活动图像，在大脑的前部分，即完成这些任务所需的

A new study adds to evidence suggesting that being bilingual is good for the brain.(20)In the study, older adults who have spoken two languages since childhood showed better mental skills than those who speak just one language.
    Earlier studies showed that bilingualism seemed to favor the development of these heightened skills. The authors of the new study say their findings provide evidence of that cognitive advantage among older, bilingual adults. Brian Gold was the lead author of the study. Dr. Gold is a neuroscientist at the University of Kentucky College of Medicine. In the study, the researchers asked people to sort colors and shapes in a series of simple exercises. Dr. Gold and his colleagues used brain imaging to compare how well three groups of people switched among these exercises. The groups were bilingual seniors, monolingual seniors and younger adults.(21)The imaging showed different patterns of activity in the frontal part of the brain, in an area used for processing such tasks. Dr. Gold says knowing a second language made no difference for the young adults. They did better at the exercises than both groups of older people. But he says the older bilingual adults appear to have built up a kind of surplus from a lifetime of increased mental activity. He says his research confirms a previous study on bilingualism among patients with Alzheimer’s, a brain-wasting disease.(22)That study showed that bilingual speakers developed more damage, but were able to think at the same level as patients with less damage. Dr. Gold says he believes the new study confirms that bilingualism can play a protective role in the brain.
20. According to the new study, what kind of people can have cognative advantage?
21. Which part of the brain do researchers study on?
22. What kind of brain condition do Alzheimers’ patients who are bilingual have?