Mental exercise can favorably______the structure of the brain just as physical exercise can change one' s bodily proportions.
【正确答案】 A
【答案解析】解析：句意：智力锻炼能够改善大脑结构，就如同体能锻炼能够改变人的身体比例。modify改变，修改。adjust调整，调节。develop发展，发达。contract缩短，订约。