I think his Japanese has improved quite a bit, hasn't it?

I am busy with work during the daytime.

He made a demand to the company for a raise in salary.

He suddenly developed acute pneumonia.

The educational methods of schools under the old system were significantly different from those of current schools.

She changed her name after getting married, but her maiden name was Tanaka.

He is suffering from a subacute illness.

He has a brash personality and tends to jump to conclusions quickly.

We held a study session at school for the underclassmen.

We were enveloped in deep sorrow due to his sudden death.