Were you sitting BY (beside) the door?
Joe parked his car BY (beside) mine.
The police station is BY the court house, isn't it?
The pencil is ON the desk.
He sat ON the fence.
Mary is not thinking well ON that occasion.
I live AT 979 A. Agoncillo St. Indang, Cavite. (JUST an example.)
Meet me AT 7-ELEVEN today.
I shall see him AT the mall.
He lives IN the country.
I'll be there IN an hour.
The child ran down the steps IN tears.