Explanation: EN covers English "on" for surfaces: El libro está en la mesa. (Sobre/encima de are also possible, but en is the everyday choice.)
Explanation: "Under" = DEBAJO DE: El gato está debajo de la cama.
Explanation: De + el contracts to DEL: al lado del supermercado. Writing "de el" is incorrect.
Explanation: "Between" = ENTRE, used without "de": entre el banco y el cine.
Explanation: Enfrente needs DE, and de + el = del: enfrente del hospital.
Explanation: "Near" = CERCA DE: Vivo cerca de la estación. Its opposite is lejos de (far from).
Explanation: Location of a specific thing uses ESTAR: Las llaves están sobre la mesa. Ser is never used for location of objects; hay introduces unknown/new things.
Explanation: Detrás always needs DE before the noun: detrás de la puerta. "De la" does not contract.