What structure is used to form the present progressive tense?

The present progressive tense is formed by utilizing the verb "to be" in its present forms—am, is, or are—followed by a verb in the -ing form. This structure effectively indicates actions that are currently happening or ongoing at the moment of speaking. For instance, when someone says "She is running," it clearly conveys that the action of running is taking place right now.

The other structures listed correspond to different tenses. The first option (was/were + verb -ing) pertains to the past progressive tense, which describes actions that were ongoing in the past. The second option (will be + verb -ing) relates to the future progressive tense, used for actions that will be ongoing in the future. Lastly, the fourth option (has/have + past participle) is indicative of the present perfect tense, which refers to actions that have been completed at the present time. Each of these structures serves a distinct purpose in English grammar, highlighting the importance of understanding verb tense to convey the correct timing of actions.