Natural language understanding is an important field of artificial intelligence.

I'm sorry, but I don't speak Japanese.

I am studying for the Japanese Language Proficiency Test next year.

He is learning how to use the second adjective.

His first adjective is 'beautiful'.

I take dietary supplements every day.

He is interested in the study of international auxiliary languages.

He understands the meaning of the proverb 'Teaching is half learning', which means that teaching leads to one's own learning.

He always keeps in mind the phrase 'If one learns without thinking, it is a waste.'