asperity

他回答时语气的尖锐让我吃了一惊。

The ___asperity in his tone when he replied took me by surprise.

这块木板的粗糙表面需要打磨光滑。

The ___asperity of this wooden board needs to be sanded smooth.

沙漠气候的严酷让探险者们难以生存。

The ___asperity of the desert climate made survival difficult for the explorers.