I have been to France once.

He finished all his work all at once.

I watched that movie three times.

She eats in small portions, so she doesn't eat a lot at once.

She tries to eat in small portions for her health.

He read a lot of books.

He reads a lot of books.

He read a large number of books.

My dream is to climb Seoraksan.

There are many books in my room.