Which word in the sentence is the action verb?

Together these gases form the comet's head.

a. Together

b. these

c. gases

d. form

d. form (verb)

Verb is an action word.

The present progressive tense is a verb tense that means the action is continuing or in the act right now. "To be" verb is mainly used to indicate and identify this verb tense present and the applying - ing of the present participle of the verb word used in the sentence. Hence based on the given sentence above we can apply the present progressive tense as:

For example:

The journalism staff is typing the yearbook copy, but another company is printing the book.

And also:

1. Past progressive tense

2. Future progressive tense

3. Future perfect progressive tense