whom for subjects or objects of infinitives

An infinitive is the word to followed by the base form of a verb. Subjects of infinitives are an exception to the rule that subjects must be in the subjective case. Whenever an infinitive has a subject, it must be in the objective case. Objects of infinitives also are in the objective case.

Example sentence with editing. Original sentence: On the subject of health care, I don't know who to believe. Revised sentence: On the subject of health care, I don't know whom to believe.

The pronoun whom is the subject of the infinitive to believe.

Exercises:

Pronoun case (who and whom) 1

Pronoun case (who and whom) 2

Pronoun case: review 1

Pronoun case: review 2

Related topic:

Infinitive phrases