看到惊喜时，她的脸上绽放出纯粹的喜悦。

Her face lit up with ___sheer delight when she saw the surprise.

他完全是凭借决心和意志力取得了成功。

He succeeded through ___sheer determination and willpower.

正是纯粹的辛勤工作让他们度过了那个艰难的项目。

It was ___sheer hard work that got them through the difficult project.