How can passive voice typically be recognized?

Recognizing passive voice relies primarily on identifying main verbs that are in their past participle form. In passive voice constructions, the subject of the sentence receives the action of the verb rather than performing it. This is usually indicated by the use of a form of the verb "to be" combined with the past participle of the main verb. For example, in the sentence "The book was read by the student," the verb "read" is in the past participle form, illustrating that the action was performed on the subject (the book) rather than by it.

In contrast, the other forms mentioned do not signify passive voice. Main verbs in their present form denote active voice where the subject performs the action. Verbs ending in "ing" also usually indicate ongoing actions in the active voice. Main verbs in infinitive form (to + verb) typically do not express completed actions in the context of passive voice. Thus, focusing on the past participle form is crucial for accurately identifying passive constructions in sentences.