答案和详解如下： 6.Which of the following is NOT a condition of a perfectly competitive market? A) Sellers make economic profits. B) Firms face elastic demand curves. C) Individual sellers each have a small share of the market. D) Indistinguishable products. The correct answer was A) The only item listed that is not a condition of a perfectly competitive market is that sellers make economic profits. In fact, sellers do not make economic profit after taking into account their opportunity costs. 7.A perfect competition has all of the following characteristics EXCEPT: A) barriers to entry don't exist. B) each competitor is small relative to the overall market. C) a large number of independent firms. D) a differentiated product. The correct answer was D) In a perfectly competitive market all the firms produce a homogeneous product. 8.Which of the following is NOT a characteristic of perfect competition? A) The products produced within a given market are homogenous. B) The demand curve for an individual firm is a vertical line. C) The size of each firm is small relative to the size of the overall market. D) There are no barriers to entry and exit. The correct answer was B) Under perfect competition individual firms have no control over price resulting in a demand schedule that is perfectly elastic or horizontal. 9.Which of the following is a characteristic of perfect competition? A) There are a few sellers. B) The products of different firms are sold at different prices. C) The competitors earn economic profits in the long run. D) There are no barriers to entry into the market. The correct answer was D) The only true statement listed in the question is that, under perfect competition there are no barriers to entry into the market. Each of the other possible answers is not a characteristic of perfect competition. While the competitors can earn positive economic profits in the short-run, they cannot earn long term economic profits due to ease of entry and exit. | 
发表于 2008-4-16 17:52
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