TOEFL Structures Skills : sentence with one clause : Skill 2 : objects of prepositions
(Be careful of objects of prepositions)
An objects of a preposition is a noun or a pronoun that comes after a preposition, such as in, at, of, to, by, behind, on and so on, to form a prepositional phrase.
Example 1 : (After his exam) Tom will take a trip (by boat)
Example 1 : With his friend, he found the movie theater.
A preposition is followed by a noun or pronoun that is called an object of the preposition. If a word is an object of a preposition, it is not the subject.
list of 50 objects of prepositions in English TOEFL Test