The document discusses the present continuous tense in both active and passive voice. It provides examples of affirmative, negative, and interrogative sentences in the active voice and explains how to change them to the passive voice. For active sentences, the structure is subject + is/are/am + -ing verb + object. For passive sentences, it is object of active sentence + is/are/am + being + past participle verb + by + subject of active sentence. The document also provides exercises changing sentences between active and passive voice.