He is writing a paper on coding theory.

String theory is a branch of physics that is a theory for understanding the basic structure of the universe.

He wrote a new paper on string theory.

He is particularly interested in string theory in physics.

He acted according to my instructions one by one.

The first day of the month is the beginning of a new month.

I have been to France once.

His first choice of school is the University of Tokyo.

I went to see a movie by myself.

He has a competitive spirit that does not allow even one defeat.