Prepositions
 “Prepositions express a relation in space between two or more entities or a relation in time between two events, or various other abstract relations such as instrument and cause.” 

 A preposition refers to the word or phrase which shows the relationship between one thing and another, linking nouns, pronouns and phrases to other words in a sentence.

For example:
(1). A relation in Place and Time:
We waited at the bus stop for ten minutes.
There is a telephone booth outside the bank.
What are you wearing underneath your coat?
She fell asleep during the lecture.
The police station is next to the shopping mall.

(2). Feelings:
Are you worried about your exam? I was surprised at your remarks.

(3). Other relationships like Instrument and Cause:
The girl stabbed the burglar with a knife. Without your support, I don’t think I can finish the project so smoothly.