Many of us believe that aperson’s mind becomes less active as he grows older. But this is not true,according to Dr. Jarvik, professor of psychiatry at the University ofCalifornia. She has studied the mental functioning of aging persons for severalyears. For example, one of her studies concerns 136 pairs of identical twins,who were first examined when they were already 60 years old. As Dr. Jarvikcontinued the study of the twins into their 70s and 80s, their minds did notgenerally decline as was expected. However, there was some declinein psycho-motor speed. This means that it took them longer to accomplish mentaltasks than it used to. But when speed was not a factor, they lost very littleintellectual ability over the years. In general, Dr. Jarvik’s studies haveshown that there is no decline in knowledge or reasoning ability. This is truenot only with those in their 30s and 40s, but with those in their 60s and 70sas well. It is true that older peoplethemselves often complain that their memory is not as good as it once was.However, much of what we call “loss of memory” is not that at all. Thereusually was incomplete learning in the first place. For example, the olderperson perhaps had trouble hearing, or poor vision, inattention, or was tryingto learn the new thing at too slow pace. In the cases where the older person’smind really seems to decay ( 退化 ),it is not necessarily a sign of decay due to old age. Often it is simply a signof depressed emotional state. 41.According to Dr. Jarvik’s studies, middle-aged and olderpersons would expect to __________. A. remember less B. reason better C. learn fewer new things D. lose no intellectual ability 42. Mental decay due to aging is ­­­­___________. A. common B. much more common than most people believe C. much less common than most people believe D. true of those over sixty 43. A long-term study of 136 pairs of twins showed that _____ . A. they lost a little ability to reason over the years B. the only factor which declined over the years was their speedwith which to perform mental tasks C. their memory was not as good as it had once been D. their minds became a bit more active as they grew older 44. According to the passage, allthe following are instances of “incomplete learning” EXCEPT __________. A. poor hearing B. bad eyesight C. lack of attention D. the attempt to learn many new things 45. What we call mental decay isusually a sign of . A. a low-spirited state B. a worsening state of health C. old age D. nervous tension