Specific language impairment (SLI) is diagnosed when a child's language does not develop normally and the difficulties cannot be accounted for by generally slow development, physical abnormality of the speech apparatus, autism spectrum disorder, acquired brain damage or hearing loss.
Perfect competition. A perfectly competitive market is a hypothetical market where competition is at its greatest possible level. Neo-classical economists argued that perfect competition would produce the best possible outcomes for consumers, and society.
In a perfectly competitive market, or one in which no firm is large enough to hold the market power to set price of a good, if a business were to sell a mass-produced good and sells all of its goods at market price, then the marginal revenue would simply be equivalent to the market price.