The document discusses the past continuous tense in English grammar. It defines the past continuous as describing actions or events that began in the past and were ongoing at another point in the past. It provides examples of sentences using the past continuous, such as "When we arrived he was having a bath" and "Caroline was skiing when she broke her leg." The document also includes a table showing the structure of the present continuous form with the subject, verb "to be," verb plus "-ing," and complement.