She smiled fleetingly before turning away.

她短暂地笑了一下，然后转身离开。

The sun appeared fleetingly between the clouds.

太阳在云层间短暂地出现了一下。

She felt fleetingly happy when she heard the news.

听到这个消息时，她短暂地感到高兴。

The memory of that day crossed his mind fleetingly.

那天的记忆短暂地掠过他的脑海。

He fleetingly glanced at his watch during the meeting.

他在会议期间短暂地看了一眼手表。

Like you might think fleetingly of someone and then have that person pop up in a dream. Or a noise like an alarm clock sounding figures in a dream narrative.

比如说，你可能会觉得有人一闪而过，又突然在梦里出现。或者你感觉在梦中的故事情节里一直回荡着像闹铃似的噪音。

Fleetingly, then, this looks accidental, an anomalous situation born out of a disease that threw everybody into a panic and then became manageable pretty swiftly.

让每人都活在恐慌中，然后又迅速得到控制这样的不正常的情况看似偶然。

Who can honestly say they're never even fleetingly been perturbed by walking under a ladder breaking a mirror or seeing a black cat cross the road in front of them?

有谁能够诚实地承认，他们从未因在梯子下走、打碎镜子或看到面前有只黑猫穿过街道而感到（哪怕是瞬间的）心烦意乱？