“come of age” 的含義要看它描述的對象是人是物。

1、如果是人，表示“成年”，即 When someone comes of age, they become legally an adult。

例句：

 The company was to be held in trust for Eddie until he came of age.

He will inherit his father’s money when he comes of age.

2、如果是物，表示“某事物得到了充分的發(fā)展/進入成熟發(fā)展期/被廣泛認可”：即 If something comes of age, it reaches an advanced stage of development and is accepted by a large number of people.

例句：

Recycling is an issue that has come of age in Britain in the last decade.

With more and more people now aware of environmental issues, ‘green’ politics has really come of age.

Coal came of age in the Industrial Revolution.