The prepositions at, on, and in
We use at to show a specific place or position.
∙ Someone is at the door.
∙ I used to live at 51 Portland Street.
We use on to show position on a horizontal or vertical surface.
∙ The cat sat on the mat.
∙ The satellite dish is on the roof.
We use in to show that something is enclosed or surrounded.
∙ The dog is in the garden.
∙ She is in a taxi.
We also use in to show position within land-areas (towns, counties, states, countries, and continents).
∙ I used to live in Nottingham.
∙ I enjoy being among my friends.
∙ The car park is behind the building.
∙ I held the pen between my thumb and fingers.
in front of
∙ The teacher stands in front of the class.
next to / beside / by
∙ In my English lesson I always sit next to/beside/by my friend.
∙ The sign hanging over/above the door read ‘No smoking’.
∙ I put the tablecloth over the table.
under / below
∙ The temperature outside was under/below 0.
∙ The woman was sheltering under a tree.