The document discusses the different tenses in English - present, past, and future. It explains the four structures for each tense: simple, progressive, perfect, and perfect progressive. For each structure, it provides examples of affirmative and negative sentences using that structure in the given tense. The tenses and their structures are: present (simple, progressive, perfect, perfect progressive), past (simple, progressive, perfect, perfect progressive), and future (simple, progressive, perfect, perfect progressive).