彼はまじめに勉強をし始めた。の英語

He began to study in earnest.

He started to study in (good) earnest.

He started to study in earnest.

He began to study with a will.

He concentrated on his studies.

He applied himself to his study.

He decided to study harder.

He studied very hard.

I found him at his books.

He is at his desk.

He is studying at his desk.

He began to learn English.

He's coming along nicely with his studies.

He began to learn English.

He studied on his own.

He studied on his own account.

He has risen by dint of perseverance―（他動詞構文にすれば）―Simple perseverance has raised him in the world.

He began to eat his breakfast.

He neglected his studies and did nothing but enjoy himself.

He began studying at an advanced age―in his old age.

He began to feel afraid.

He started to go to bed early.

He set to work with unrestrained zest.

He works like fury―like thunder―like hell―like the devil―like anything.

He plugged away at his lessons.

He is diligent in his study.

He is intent on his studies.

He always studies hard.

He preceded his lecture with an introduction.

He studied like one possessed.