Answer:
Prepositions.
Step-by-step explanation:
Prepositions are parts of speech that tell us the time, location, direction, place, or even relationships in a sentence. They are used to introduce an object and are placed before nouns or pronouns.
Examples of prepositions are "at, in, under, by, to, behind, since" etc. These prepositions can be used to signify the time, location, or space in a sentence.
Examples of these prepositions in a sentence are-
Time- I have been studying since morning.
Space- My umbrella was under the bed.
Location- I was taking a class in the hall.