You would have to be pretty hard-hearted not to feel something for him.

你必须是非常铁石心肠才能对他没有一点同情。

《柯林斯英汉双解大词典》

"You must try hard," replied the kind-hearted boy.

“你必须努力尝试，”善良的男孩回答说。

youdao

In a final pair of experiments, the scientists tested metaphors like "hard-hearted" and "she's a rock" by first having people touch either a wooden block or a soft blanket as part of a magic trick.

在最后一组实验中，科学家测试诸如“铁石心肠”、“她像块石头”这类比喻。首先，作为魔术的一部分，人们先是触摸一个木块或是一张柔软的毯子。

youdao

I've been broken-hearted and broken some hearts, I've tried running hard from my pain.

NPR: Judy Collins, From Both Sides Now

Under the guidance of charismatic coach Jurgen Klopp, whose popularity has seen a pop song written about him, Dortmund's run to the final has left even the most hard-hearted of seasoned aficionados willing on the men in yellow and black.

CNN: Wieners to Wunderbar: How Germany became uber-cool

You can't accuse those who ordered us to drop blankets of being hard-hearted!

NPR: 'Battle for Peace' in Iraq Echoes Vietnam