Now thrust could be generated (for “free” again) at periapsis, progressively increasing the altitude of apoapsis.

这时可以「免费」在近产生推力，高度提升。

The repeated thrust applications at apoapsis would raise periapsis from inside to outside the stationary orbit.

重复在施以推力，会近由同步轨道内提升到同步轨道外。