Concentrated

I concentrated my attention on the subject.

The student concentrated on his subject.

I concentrated my attention on the lecture.

I concentrated all my energies on the problem.

I concentrated my effort on the study.

I concentrated my attention on the little things of history.

The general concentrated the soldiers in Paris.

The biologist concentrated on observing the phenomenon.

Taro concentrated on memorizing English words.

I concentrated on what he was saying.