A smile passed fleetingly across his face.

笑容从他的脸上一闪即逝。

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。

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。

The quarks and gluons indeed break out of confinement and behave collectively, if only fleetingly.

夸克与胶子确实打破牢笼而表现出集体行为，虽然这种状态转瞬即逝。

In Mary's case, her features had fleetingly exhibited despair when the interviewing doctor asked about her plans.

在玛丽这个案例中，当医生询问她的打算时，她的面部特征在一瞬间显示绝望的表情。