caprice

他突然决定取消旅行计划，这种反复无常真是让人难以理解。

His sudden decision to cancel the trip was just another ___caprice that confused everyone.

她一时心血来潮，在拍卖会上出价五千美元竞拍一件抽象雕塑，而她此前从未收藏过艺术品。

On a ___caprice, she bid five thousand dollars for the abstract sculpture at the auction, though she had never collected art before.

他离开律师事务所去开一家面包店的决定并非一时冲动，而是精心筹划了五年的计划。

His decision to leave the law firm and open a bakery was not a ___caprice but a plan he had nurtured for five years.