It doesn't have to be a real container to contain it It's just an imaginary boundary there.

它不必是,一个真实的容器,只是一个想象的边界。

麻省理工公开课 - 热力学与动力学课程节选

"Gulf War illness isn't some imaginary syndrome, " said Ken Robinson, the senior intelligence officer for the initial Department of Defense investigation into Gulf War illness in 1996-97.

CNN: Gulf War illness is real, new federal report says

Jim isn't quite imaginary.

WSJ: How to Ace a Google Interview

But this rivalry isn't just an imaginary one.

FORBES