A sudden whim to buy a cream cake.

去买奶油蛋糕的一个突然的怪念头，。

He had a sudden whim to go sailing today.

今天他突然想要去航海。

He had a sudden whim to take a midnight walk.

他有一个突然的怪念头，半夜里散步。

He had just about decided to forget his sudden whim and go to bed when the cage gave a jerk and began to ascend.

最后他终于决定忘记这偶发的奇想，打道回府去睡觉时，铁笼却猛地一晃，开始上升。