If a non-Jew lights a lamp on Shabbos, a Jew may use the light; if the non-Jew lit it for the Jew, then it is prohibited. If a non-Jew filled a vessel to water his animals, a Jew may also water his animals from that vessel, after the non-Jew; if the non-Jew filled the vessel for the Jew, then it is prohibited. If a non-Jew places a ramp to disembark from a ship on Shabbos, a Jew may use it to disembark after him; if the non-Jew made the ramp for the Jew, then it is prohibited. It once occurred that Rabban Gamliel and the Elders arrived on a ship on Shabbos and a non-Jew assembled a ramp for them to disembark, and they did.
Pieces of furniture may be moved on Shabbos with their doors, even if the doors became detached on Shabbos. This is because these doors are not like the doors of a house, which are not designed to be moved.