A smile passed fleetingly across his face.

笑容从他的脸上一闪即逝。

《柯林斯英汉双解大词典》

She was only their temporary custodian, she said, a form and a face caught fleetingly by the movie camera or posing, in soft focus, behind the hard stones.

她说，她只是他们的临时监护人，被电影摄像机迅速捕捉、在硬石头后面柔焦的聚光灯下摆姿势的一个人罢了。

youdao

He enrolled fleetingly in high schools in London and Sarajevo, Yugoslavia, but rarely attended.

他曾短暂的在伦敦及南斯拉夫萨拉热窝入高中上学，但很少上课。

youdao

He mentioned Simpson-Bowles fleetingly in his State of the Union speech a month later.

WSJ: Fred Barnes: Obama and the Back-to-the-Future Campaign

Perhaps pity was a truer description of what I felt for him, however fleetingly.

NPR: Sergeant Notes Odd Rituals of War in Afghanistan

Bringing the outside in and the inside out even fleetingly can make a house feel like an open-air paradise.

FORBES: 8 Incredible Open-Air Homes