The simple and perfect tenses have progressive forms that describe actions in progress.
Present progressive (am, is, are + present participle)
Past progressive (was, were + present participle)
Future progressive (will + be + present participle)
Present perfect progressive (have, has + been + present participle)
Past perfect progressive (had + been + present participle)
Future perfect progressive (will + have + been + present participle)
NOTE:The progressive forms are not normally used with mental activity verbs such as believe, know, and think.)
Some of these verbs, however, have special uses in which progressive forms are normal (We are thinking about going to the Bahamas).
Complete survey of tenses
Exercises:
Verb forms and tenses 1
Verb forms and tenses 2
Using verbs: review