The operator is operating the machine.

He is already an adult, so he can make his own decisions.

He is a very talented arranger.

He is a famous lyricist.

He is an expert in computer science.

We need to choose a candidate for the new president.

Who is the producer of this movie?

He was chosen as the challenger for the next match.

He is the administrator of this website.

His grandfather was a survivor of the Hiroshima bombing.