I left my bedding ______ the station.

Concept

The preposition of place 'at' marks a position thought of as a single point or a specific named location — a station, a bus stop, a gate, an address. We use 'at' when the location is treated as a reference point rather than a surface ('on') or a three-dimensional interior ('in').

Application

Here the station is named as the specific place where the bedding was left, i.e. a point of reference, not a surface it rests on or a space enclosing it. So the slot takes 'at': "I left my bedding at the station."

Contrast

• 'on' signals contact with a surface (on the table, on the floor); it does not fit a named place treated as a point.

• 'in' signals being enclosed inside a volume (in a box, in a room); it would force the reading 'inside the station building' rather than the general location.

• 'upon' is a formal/archaic variant of 'on' and likewise implies resting on a surface, so it is unidiomatic with a station as a location.

Hence the location preposition that names the station as a point is the natural completion.