Patrick S. answered 06/27/21
M.A. English with 30 years of test-prep experience and scoring.
If you are running, "running" is a verb with the auxiliary verb "are" showing the tense. If you say "Running is good exercise," then "running" is being used as a noun and in this use it is called a gerund.
Afzal S.
Good06/27/21
Afzal S.
Nice Explanation06/27/21