他对参加这次比赛非常热心，每天都积极训练。

He was very ___keen on joining the competition and practiced hard every day.

这把剪刀的刃口非常锋利，可以轻松剪开厚纸板。

The scissors have a ___keen edge that can easily cut through thick cardboard.

她敏锐的头脑总能迅速抓住问题的核心。

Her ___keen mind always grasps the essence of problems quickly.

她对音乐有着强烈的热爱。

She has a ___keen love for music.