他在我前面走着，然后突然就消失得无影无踪了。

He was walking ahead of me on the path and then he just ___vanished ___into ___thin ___air.

你希望逃避的问题不会简单地消失得无影无踪。

The problems you hope to escape do not simply ___vanish ___into ___thin ___air.

调查期间，关键证人似乎消失得无影无踪了。

During the investigation, the key witness seemed to ___vanish ___into ___thin ___air.