stumping

The contestant's stumping on the final question was obvious to everyone.

用法提示：stumping为名词，表示被难住这一行为。

After a brief stumping, she admitted she didn't know the answer.

用法提示：stumping为可数名词，此处带不定冠词a，指一次被难住。

The teacher was familiar with such stumpings and always offered helpful hints.

用法提示：stumpings为stumping的复数形式，指多次被难住的情况。