当代研究生英语读写教程完形下册

Unite one:

There are two factors which determine an individuals intelligence. The first is the sort of brain he is born 1.with .Human brains differ considerably, 2.some being more capable than others .

3.But no matter how good a brain he has to begin with ,an individual will have a low order of intelligence 4.unless he has opportunities to learn. So the second factor is what 5.happens to the individual-the sort of environment in which he is brought

6.up .If an individual is handicapped 7.environmentally, it is likely that his brain will 8.fail to develop and he will 9.never attain the level of intelligence of which he is 10.capable. The importance of environment in determining an individuals intelligence can be

11.demonstrated by the case history of the identical twins, Peter and John. When the twins were three months old, their parents died, and they were placed in 12.separate foster homes. Peter was reared by parents of low intelligence in an 13.isolated community with poor educational 14.opportunities. John, 15.however, was educated in home of well-to-do parents who had been to college, This environmental 16.difference continued until the twins were

17.in their late teens, 18.when they were given tests to 19.measure their intelligence. Johns I.Q was 125,twenty-five points higher than the 20.average and fully forty points higher than his identical ，，，