如果我有三個兒子，怎樣向人介紹。

I have three sons. The eldest son is a programmer; the second son is a teacher; the youngest son is a police officer.
The elder son is a programmer and the younger son is a police officer.

除了 son 之外，口語亦會用 boy 。
I have 3 boys: a programmer, a teacher and a cop (police).
最大(即最老) eldest
最結(即最年輕) youngest

I have 3 sons. The oldest one is working for programmer and the second one is Teacher. The last one is Policeman.

I have two sons. The oldest one is working for programmer and the last one is Policeman.

I have 3 sons, the eldest son is a programmer, the second son is a teacher, the third son is a policeman.
大的和細的, the first son and the second son.