A、They have better memories than normal people. B、They can focus on multiple tasks at a time. C、Their brains have been trained a

Now listen to the following recording and answer questions 20 to 22.
    Now I would like to talk about the deterioration of our brain. Neuroscience tells us that we can delay this process. In some instances, we can reverse brain deterioration by engaging in some pretty specific activities, most of which we would consider hobbies. Here are some of them.
    First, learn a new language. Several areas of the brain are used as we take in sound, give it meaning, and then respond to it—areas in all.(20)Bilingual people have more gray matter in their language centers. They can focus on more than one task at a time because parts of their brain that relate to reasoning, planning, and memory are more developed. Again, scientists began to study this in children first, looking at those in whose households a foreign language was spoken, but in whose schools only English was spoken. Being forced to take in sounds from two different languages and "sort out" which language was being heard forced these areas of the brain into greater functioning. Now, it is also known that learning a language at any stage in one’s life has the same forceful effect on the brain making it smarter.
    Next, engage in cumulative learning. Cumulative learning is defined as that process by which we take what we already know and layer new information of the same type on top of that. For example, math is cumulative learning. Children first learn basic functions. Then they learn how to use those basic functions to solve word problems. Next, they learn something else, using basic functions to solve equations. Every layer goes on top of what was learned before. As we age, and especially as we leave the workforce, we tend to cease cumulative learning activities.(21)However, research says if we continue to engage in them we sharpen memory, problem solving, and language. Maybe we should all take a math or writing class in our senior years!
     (22)Last but not least, exercise your brain with puzzles and games. We need to think of our brains as both computers and muscles. The more information we put into our brains, the more functions they can perform. Likewise, the more we exercise our brains, the stronger they function. There are continually new connections that are made when we take in information, engage in thinking, and force ourselves to remember things. Crossword puzzles, deductive thinking activities, and strategic games such as chess or even some video games, force our brains to take in new information and make new connections.
20. What does the speaker say about bilingual people?
21. What can we get from cumulative learning activities according to the research?
22. What’s the benefit of exercising our brains with puzzles and games?