This document discusses English modal verbs used to describe abilities. It explains that "can" is used for present abilities, "could" is used for past abilities or possibilities, and "be able to" is used to talk about a specific past event or ability. It provides examples of sentences using each modal verb to demonstrate talking about abilities in the present, past, and a specific past event. The document concludes by asking the reader to practice using all the modal verbs to discuss abilities in different tenses.