The document discusses the past continuous and present continuous tenses in English. The past continuous is used to describe an action that was happening in the past but was not completed. It is formed using the past tense of "to be" plus the present participle of the main verb. The present continuous describes an ongoing action in the present. It uses the present form of "to be" and the present participle. Both tenses can be used affirmatively, interrogatively, or negatively following consistent structures.