The document discusses the present perfect tense and passive voice in English.
The present perfect tense uses the auxiliary verb "have" plus the past participle to talk about actions that began in the past but continue in the present. It is often used without specific time expressions. Examples are provided of affirmative and negative sentences as well as questions.
The passive voice is used to emphasize the object of the sentence rather than the subject. It is formed using a form of "to be" plus the past participle. The passive voice can be used to describe a process or the result of a process without specifying who performed the action. Examples are given comparing active and passive sentences.