[解析]
(1)B 标题概括题.文章主要讲述了影响智力的因素有哪些,通过举例子说明环境主要影响人的智力.故选B.
(2)B 细节题.根据文章内容"Mark's I.Q.was 125,twenty﹣five points higher than the average and fully forty points higher than his identical brother."可知.人的平均I.Q为100.故选B.
(3)C 细节题.根据文章内容"Peter was reared by parents of low intelligence in an isolated community with poor educational opportunities.Mark was reared in the home of well﹣to﹣do parents who had been to college.He was read to as a child,sent to good schools,and given every opportunity to be stimulated intellectually.This environmental difference continued until the twins were in their late teens,when they were given tests to measure their intelligence."彼得被父母养育在一个缺少教育机会的封闭社区.马克是生长在富裕的上过大学的父母家里.他读到作为一个孩子,送到好学校,并给予每一个机会刺激智力.这环境差异一直持续到他们十几岁,当他们接受测试是发现马克的智力比彼得高.故选C.
(4)C 细节题.通过文章对彼得和马克的一个测试说明人的智力可以通过教育来提高.故选C.