IN....ON....AT

Rules for Usage:
PREPOSITIONS THAT ESTABLISH RELATIONSHIPS IN SPACE

The prepositions “in,” “at,” and “on” for indicating place and location. The general rule is to use “in” for an enclosed space, “at” for a point, and “on” for a surface. Here are some specific guidelines for their use in American English:

Use “in” for spaces: “They always meet in a secret room [in a suburban hotel, in a parking lot, in a farm, in a ricefield].”

Use “in” for names of specific land areas: “She lives in a quiet town [in Tagaytay, in Cavite, in Southern Tagalog, in the island of Palawan, in the Philippines, in Southeast Asia].

Use “in” for bodies of water: “That kind of fish thrives in freshwater [in the river, in the lake, in streams, in the sea].”

Use “in” for lines: “The registrants are in a row [in a line, in a queue].”

Use “at” to indicate points: “You’ll find us at the entrance [at the taxi stand, at the supermarket, at the intersection].”

Use “at” for specific addresses, as in “She lives at 40 Lilac St.”

Use “on” for names of streets, roads, avenues, and boulevards: “Her apartment is on San Pablo Street [onOrtigas Avenue, on Santolan Road, on Roxas Boulevard].”

Use “on” for surfaces: “There’s a large stain on the floor [on the wall, on the ceiling, on the roof].”

The prepositions “in,” “at,” and “on” for indicating location.

Use “in” in these cases: “The children are in the kitchen [in the garden, in the car, in the library, in the class,in school]. (The article “the” is mandatory except for the fourth and last example.)

Use “at” in these particular cases: “She was at home [at the library, at the office, at school, at work] when we arrived.”

Use “on” in these particular cases: “They are on the plane [on the train, on the boat].”

Some locations, though, don’t need a preposition between them and the verb: “They sleep downstairs [inside, outside, downtown, upstairs, uptown].”