4 IMPORTANT POINTS ON PREPOSITIONS - A PART OF SPEECH IN ENGLISH GRAMMAR

 Prepositions are a class of words that indicate relationships between nouns, pronouns and other words in  a sentence.

Most often they come before a noun. They never change their form, regardless of the case, gender etc. of the word they are referring to.

Example: after class

               ; at home

                : before Tuesday

                : In London

some common prepositions are:

about

across

through

since

Prepositions typically come before a noun :

on fire

with pleasure

A preposition usually indicates the temporal, spatial or logical relationship of its object to the rest of the sentence.

: The book is on the table

: The book is beside the table

: She reads the book during the class

In each of the preceding sentences, a preposition locates the noun "book" in space or in time.