In English, prepositions can be correctly used in several ways: they may describe a place, a time or the conditions necessary for an event to take place, among other situations. When used correctly, a preposition relates words to other words in the same sentence.
The simplest prepositional phrases contain only a preposition and a noun, for example, "at home." You can add a subject and modifiers to this phrase to make a sentence.
To use a preposition to describe time, use it to describe when something will happen. For example, "Let's meet around seven p.m." Prepositions can also refer to the past, for example, "In 1492."
When describing conditions, link the necessary condition to the sufficient condition with a preposition. For example, "I won't let you leave without saying goodbye." Here, the preposition "without" shows that saying goodbye is necessary for one person to let the other one leave.