The document discusses the difference between active and passive voice in sentences. It provides examples of sentences written in active voice and their passive voice equivalents. The key difference between active and passive voice is that active voice uses the verb form "verb+ing" while passive voice uses the past participle form of the verb. Passive voice constructions feature the subject receiving the action rather than performing it. Various tenses like simple present, past, future etc. are discussed along with their active and passive forms.