hard at work

前置詞句

Labouring with great effort and diligence; working hard.

日本語の意味

大変な努力をして働いている / 精を出して働いている / 懸命に働いている

They were hard at work preparing the presentation late into the night.

彼らは夜遅くまでプレゼンテーションの準備に懸命に取り組んでいた。

意味（1）

Labouring with great effort and diligence; working hard.

I'm sorry I can't make it to the party—I'm going to be hard at work all day.