I got a seat opposite a middle-aged man with sharp eyes, who kept watching a young woman in a window seat with a little boy on her lap.

我坐在一个中年男子对面，他目光敏锐，一直盯着一位坐在靠窗座位上的年轻女子，她腿上坐着一个小男孩。

youdao

Gathered together, the old, the middle-aged and the young studied side by side and encouraged each other.

老、中、青济济一堂，共同学习，相互激励。

《新英汉大辞典》

"Everyone wants free time to do the things they want to do, young, middle-aged or old," said Richard Morin, of the Pew Social &Demographic Trends Project, which conducted the survey.

开展该调查的“皮尤社会与人口趋势项目”的理查德•莫林说：“无论青年、中年还是老年人，每个人都希望有空余时间去做自己想做的事情。”

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Migraine headaches are most common among young adults and middle-aged people.

VOA: special.2009.03.18

Prostate cancer is rare in the under 50's, but more 'young middle - aged' men are being diagnosed.

BBC: Prostate cancer research announced

Reporters from Hong Kong's South China Morning Post saw villages "abandoned" by the young and middle-aged, leaving children and the elderly behind.

FORBES: Magazine Article

"We have got some very good young and middle-aged players in Josh's position - there are some pretty high-quality guys there, " added Ashton.

BBC: Vainikolo named in England squad