1.   However, you should remember that you may not be able to fill all the hollow cavities in each wall this way.

2.   Imagine it as the hollow cavity of a Jurassic fossil.

3.   The compression is achieved by bombarding tiny hollow spheres with powerful laser beams, vaporizing and imploding them, thereby compressing the hydrogen sealed within their hollow cavities.

4.   They were lifting up a sidewalk newspaper vending box and stashing their bed rolls and belongings in the hollow cavity under the newspaper compartment.