填空题

There are two factors that determine an individual’s intelligence. The first is the sort of brain he or she was born with. Human brains differ (36) . Some people’s brains are more capable than others’. But no matter how good is a brain he or she has to begin with, an (37) will have a low level of intelligence unless he or she has opportunities to learn. So the second factor is what happens to the individual, that is, the sort of (38) in which he or she is brought up. If an individual is handicapped environmentally, it is (39) that his or her brain will fail to develop and he or she will never reach the level of intelligence which he or she is capable of. The importance of environment in (40) an individual’s intelligence can be (41) by the case history of the identical twins, Peter and Mark. Because they are identical twins, they had identical brains, and their growth (42) were the same, When the twins were three months old, their parents died. And they were (43) by different families. (44) Mark was raised in the home of well-to-do parents who had been to college. His parents told him stories since he was very young, and in time sent him to schools. He was given every opportunity to be stimulated intellectually. (45) .Mark’s I.Q. was 125, 25 points higher than the average and fully 40 points higher than his identical twin brother. (46) .