This document discusses verb tenses using the verb "to be" followed by a present or past participle. It explains that "be + present participle" is used when the subject is performing the action of the verb, while "be + past participle" is used when the subject is not performing the action. Examples are provided of regular and irregular past participles. The conclusion reiterates that the key is determining whether the subject is actively doing or has completed the action to choose the correct participle.