During the 9th century scientists
found that when certain parts of the brain of a man were{{U}} (36)
{{/U}} , he would lose the{{U}} (37) {{/U}} to do certain things.
And so, people thought that each part of the brain does a different{{U}}
(38) {{/U}} . But modern research has{{U}} (39) {{/U}} out that
this is not so, for it is not{{U}} (40) {{/U}} to say{{U}} (41)
{{/U}} what each part of the brain does. In the past fifty
years there{{U}} (42) {{/U}} a great increase in the amount of
research{{U}} (43) {{/U}} on the brain. Chemists and biologists have{{U}}
(44) {{/U}} that the{{U}} (45) {{/U}} the brain works it is
not so{{U}} (46) {{/U}} as people in general may think. Chemists tell us
that 100,000 chemical changes{{U}} (47) {{/U}} in the brain every
second. Some recent researches also{{U}} (48) {{/U}} that we can
remember everything{{U}} (49) {{/U}} happens{{U}} (50) {{/U}}
us. We{{U}} (51) {{/U}} not be able to recall (回忆) the things we've
heard and seen, but it is all kept there in the storehouse of the human
mind. Earlier scientists thought the power of one's brain got
weaker as one grow{{U}} (52) {{/U}} . But it is now thought that is
not{{U}} (53) {{/U}} . As long as the brain is{{U}} (54)
{{/U}} {{U}}(55) {{/U}} exercise it keeps its ability. It has been
proved that an old person who has{{U}} (56) {{/U}} been active in the
mind has a{{U}} (57) {{/U}} mind than a young person who has only
done{{U}} (58) {{/U}} work{{U}} (59) {{/U}} using much of his
brain. It is now thought that the{{U}} (60) {{/U}} work we give our
brains, the more work they are able to do.