Text There are two aspects which determine an individual's intelligence. The first is the

Text

There are two aspects which determine an individual's intelligence. The first is the brain he is born【C1】______. Human brains differ considerably,【C2】______being more able than others.【C3】______no matter how good a brain he has to begin with, an individual Will have a low order of intelligence【C4】______he has opportunities to learn. So the second aspect is what【C5】______to the individual — the environment in which he is brought【C6】______. If an individual is handicapped【C7】______, it is likely that his brain will【C8】______to develop and he will【C9】______attain the level of intelligence of which he is【C10】______. The importance of environment in determining an individual's intelligence can be【C11】______by the case history of the identical twins, Tom and Mike. When the twins were three months old, their parents died, and they were placed in【C12】______foster homes. Ton, was reared by parents of low intelligence in an【C13】______community with poor educational【C14】______. Mike,【C15】______was educated in the home of well-to-do parents who had been to college. This environmental【C16】______continued until the twins were【C17】______their late teens,【C18】______they were given test to【C19】______their intelligence. Mike's I. Q. was 125, twenty-five points higher than the【C20】______and fully forty points higher than his identical brother.

【C1】

A．for

B．by

C．with

D．in