He was a young fellow, very green, very immature.

他是个年轻的家伙，没什么经验，很不成熟。

《柯林斯英汉双解大词典》

This is An An, a young fellow.

这位呢叫安安，是个小伙子。

youdao

A young fellow that age tied to a woman of forty-five.

大好年纪的小伙束缚到一个四十五岁的女人身边。

youdao

No matter how I look at this issue, I cannot escape being troubled by the fact that we have in place a policy which forces young men and women to lie about who they are in order to defend their fellow citizens."

VOA: special.2010.02.06

"A young fellow who managed to escape was the one who told us about it, but we don't really know anything else, " Dominguez said.

CNN: 11 young people go missing from bar

At the intimate Christmas market outside, a young fellow at a stall offered us several samples of snaps warming, herb-infused Scandinavian spirits and a plate of heart-shaped waffles dusted with sugar and jam to eat while we chatted about his hometown.

WSJ: Visiting Copenhagen in Winter

Those bewitched by the John-John idea saw the grown man as a frivolous young fellow floating carelessly on the pleasures of life.

CNN: Brought up to be a good man