But finding new shopowners to fill empty space is increasingly difficult.

VOA: standard.2009.12.20

So they weren't hitting anything, we're dealing with mostly empty space.

但他还意识到，当它们碰到东西的时候。

麻省理工公开课 - 化学原理课程节选

So do empty food containers, space boots,life support systems and an American flag.

VOA: special.2010.03.02