我想知道那个男孩是谁。

I wonder whom that boy is.

那边唱歌的那个男孩是谁？

Who is the boy that is singing over there?

吉姆：韩梅，那个男孩是谁?

JIM：Han Mei,who's that boy?

坐在你边上的那个男孩是谁? ?。

Who o's the boy sitting next to you?

那个男孩是谁？他是刘涛。他是一个学生。

S that boy? He's Liu Tao. He's a student.