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

1.When advertising expenditure is increased, which of the aggregate and average (cost and revenue) curves shift their positions? Explain the direction of the shift.As an industry moves from being a monopoly to amonopolisticallycompetitive one (due to the entry of new competitors as the monopoly's patents expire, for example), what happens to the elasticity of the demand curve facing the firm?Why?

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 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?