The Grammar of 'Complain' Aim: This page is to help you choose the right part of speech for complain / complaint / complained etc. On this page: Grammar notes, prepositions, a situation and an exercise. Grammar Notes
Word Part of Speech Examples
to complain infinitive verb I would like to complain about your services.
complains third person verb He complains all the time.
complained past tense verb Customers complained about our services last year.

I complained to the customer service representative 2 weeks ago.

have complained present perfect verb Recently several customers have complained about this problem.
complaining continuous verb Customers are complaining about our services.
adjective We value complaining customers because they help us to improve.
gerund Complaining makes me feel better.
complaint noun I have received a complaint about our services.
(meaning: obedient / co-operative)
adjective The company is a compliant customer.