嵌套类 StudentImpl 是 Student 特征的实现,因而提供了必需的 get()/set() 方法对。
Researchers measure a trait, such as sensation-seeking, in identical and fraternal twin pairs growing up in the same environment, and consider whether the two twin types are equally similar.研究者检测一种特性,例如感觉的寻求,在相同的环境下,相同的双胞胎兄弟成长,考虑是否两个双胞胎类型是完全相似。