Week 3 Discussion Economics, Ch. 9: Businesses and the Costs of Production, homework help

What is the difference between accounting costs and economic costs?
Why do economic costs include both explicit (revealed and expressed) costs and implicit (present but not obvious) costs?
What are the differences between fixed and variable costs and among total, average, and marginal costs?

What is the difference between a market structure and a characteristic of market structure?
What are the main characteristics of the four basic market models?
How can purely competitive firms use the total-revenue-total-cost approach to maximize profits or minimize losses in the short run?

How does the long run differ from the short run in pure competition?
How do profits and losses drive the long-run adjustment process of pure competition?

What are the barriers to entry that shield pure monopolies from competition?
What are the economic effects of monopoly?

Why are monopolistic competitors only earning a normal profit in the long run?
Why does monopolistic competition deliver neither productive nor allocative efficiency?

Each question min of 200 words. APA format.
Reference:
McConnell, C., Brue, S., & Flynn, S. (2015). Economics Principals, Problems, and Policies (20th ed.).
IMPORTANT:
(1) each answer must be longer than a few sentences [each must be long enough to support substantive discourse (description alone is not substantive)]; (2) try to integrate personal/professional experience where possible; (I work in marketing) and, (d) I expect evidence of research [I expect APA formatted citations to required readings and outside sources where possible, the more references per post and the more outside sources the better.