图书馆的角落里有一个安静的小空间，专门用于阅读。

There's a quiet ___sub-space in the corner of the library dedicated to reading.

这个二维平面构成了三维空间中的一个子空间。

This two-dimensional plane forms a ___subspace within the three-dimensional space.

飞船在亚空间中航行可以避开常规空间的障碍。

The starship navigates through ___sub-space to avoid obstacles in normal space.