A、Physical work. B、Mental work. C、Scientific knowledge. D、Nourishing food. B

Earlier scientists thought that during a man’ s lifetime the power of his brain decreased. But it is now thought that this is not so. As long as the brain is given plenty of exercise it keeps its power. It has been found that an old person who has always been mentally active has a quicker mind than a young person who has done only physical work. It is now thought that the more work we give our brains, the more work they are able to do.
    Other people now believe that we use only 1% of our brains’ full potential. They say that the only limit on the power of the brain is the limit of what we think is possible. This is probably because of the way we are taught as children. When we first start learning to use our minds we are told what to do, for example, to remember certain facts, but we are not taught how our memory works and how to make the best use of it. We are told to make notes, but we are not taught how our brains accept information and which is the best way to organize the information we want our brains to accept.
26. What did earlier scientists think about the power of the human brain?
27. What can enlarge the brain’ s capacity?
28. How well do we actually use our brain’ s potential according to the speaker?
29. What may limit the use of the brain’ s power?
30. What can be inferred from the passage?