他父亲严肃的表情让每个人都紧张。

His father's ___stern expression made everyone nervous.

这份报告受到了专家的严厉批评。

The report received ___stern criticism from experts.

他严厉地瞪了他妹妹莎拉一眼，但这并没有阻止她恶意地咧嘴笑。

He shot his sister Sarah a ___stern look which did not deter her from grinning maliciously.