The definition of a trial is  a hearing in a court case, a test or a hardship. An example of trial is the court case of an accused robber. An example of trial is the use of a small size bottle of shampoo to sample the product.
An example of a market that meets all four conditions for perfect competition is: wheat. A market structure with many sellers and many buyers is: perfect competition. Offering products of different tastes and shapes is an example of: nonprice competition. An example of a barrier to entry is: high start-up costs. Compared to a market with perfect competition, a monopoly often has: higher prices and fewer goods. In many industries, deregulation has resulted in: lower prices for consumers. A market that is an oligopoly has: a few firms dominating the market.
The spectrum of business enterprise ranges from perfectly competitive firms to monopoly. Between these two extremes lies the business landscape in which the vast majority of firms actually operate. Imperfect competition is a market structure with more than one firm in an industry in which at least one firm is a price setter. An imperfectly competitive firm has some monopoly power. This power depends on product differentiation that leads to a downward sloping demand curve, or it may result from the interaction of rival firms in an industry with only a few firms.