Complex sentence: The Doctor finds his TARDIS nearby, Gibbis asks for a lift home and The Doctor then takes Amy and Rory back to Earth, believing it best for the two to stop travelling with him before they end up killed.
Split into simpler sentences: The Doctor finds his TARDIS nearby, Gibbis asks for a lift home. He then takes Amy and Rory back to Earth, believing it best for the two to stop travelling with him before they end up killed.