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1·The jet fighter let go a silver vapour trail and disappeared at once in the blue.

那架喷气战斗机放出了一条银白色的雾化尾行，随即消失在天空中了。

2·The vapour trail, which some said appeared to be coming from a missile moving vertically into the sky, was filmed by the news helicopter near Los Angeles, in southern California.

那道蒸汽轨迹是广播公司的直升飞机在离洛杉矶不远，加利福尼亚南部拍摄到的，有人说，那道轨迹似乎像来自于一个垂直飞向天空的导弹。

3·When a charged particle zips through the chamber, the vapour condenses into a trail of droplets showing the particle's path and, if the box is placed in a magnetic field, its electrical charge.

当一个带电粒子快速穿越云室时，水汽会凝结形成一串小液滴，这样便标识出了该粒子的路径；若将容器置于一个磁场中，还能知道粒子所带电荷的性质。

4·Some physicists said earlier on Tuesday they believed the trail had been left by an aircraft, and that on a clear day vapour can appear to rise vertically as the result of an optical illusion.

星期二早些时候，一些物理学家说，他们相信那道轨迹是飞行器留下的，而且，在天气晴朗时，由于人的错觉，蒸汽会显得像是垂直上升的。