1.infancy 婴幼儿时期

He showed his talents in his infancy.

他在婴儿时期就展现出了天赋。

2.school children 学龄儿童（6-12岁）

School children should receive education.

学龄儿童应该接受教育。

3.adolescence 青春期

Adolescence is a key period in one's life.

青春期在人的一生中至关重要。

4.thirties 而立之年

He is in his thirties.

他处在而立之年。

5.middle age 中年

Mother is entering into her middle age.

妈妈正在步入中年。