both the father and mother earn money for the family...both做什么成分,是主语还是定语

both在句子中可做主语,宾语,同位语.
当它代指某物是,根据所在位置不同做主语,宾语.比如：
Both are right.（主语）
I like both.（宾语）
例如你给出的那一句,both 后以给出了某物（这里是某人）the father and mother ,则做同位语.
例如：Both pencils are mine.如果both用在earn前面呢，也是同位语吗对。就等同于the father and mother= both