The use f preposition of place is one of the most confusing grammar rules, but they are actually quite simple if you know the rules. The most commonly confused preposition of place are in, on and at. Remember the following general rules.
1.) In is usually used to refer to an enclosed place. For example, in a box, in the room, in Japan. Notice that enclosed can mean a very small or very large place.
2.) On is usually used to refer to a surface. Use on when you referring to a thing attached to something. For example on a table, on the board, on the chair.
3.) At is used to refer to a particular point or place. For example, at the bank, at the entrance, at my girl friend’s house. Again, notice that the “point” can be enclosed or not.
There are many prepositions, but these three are the most confusing. » Read more