Please, I need some help answering these questions. I would like to understand the main idea with a clear and well-described response. Thanks and stay well.

Please use your own words, do not use already posted answer, Thanks.

2. Why is it that firms can earn profits in the long run in monopoly and oligopoly but not in monopolistic competition and perfect competition? What can firms do in a monopolistic competition or perfect competition to make the short run last as long as possible since they can only make profits in the short run? Have you observed any firms employ such tactics? Can you give some examples?