阅读理解细节题答题策略例题解析：
　　 例题
　　 • Robert Spring spent 15 years ______.
　　 • A. running a bookstore in Philadelphia
　　 • B. corresponding with Miss Fanny Jackson
　　 • C. as a forger
　　 • D. as a respectable dealer
　　 • Source sentence: Robert Spring, a 19th century forger,was so good at his profession that he was able to make his living for 15 years by selling false signatures of famous Americans.
　　 例题
　　 • Specialization is encouraged because _________.
　　 • A. people can use their money to buy whatever they want
　　 • B. people do not need to make a complete product for exchange
　　 • C. people make a great contribution to the manufacture of a product
　　 • D. people cannot use their money to buy whatever they want
　　 • Source sentence: Specialization, which is vital to an advanced economy, is encouraged, because people whose output is not a complete product but only a part of one in which many others are involved can be paid an amount equivalent to their share of the product.
　　 例题
　　 • A barter economy is one in which __________.
　　 • A. value is decided by weight
　　 • B. value is decided by number
　　 • C. money is used and goods are not exchanged
　　 • D. goods are exchanged and money is not used
　　 • Source sentence: In a barter economy it would be necessary to determine how many plates were worth one hundred weight of cotton, or how many pens should be exchanged for a ton of coal. which would be a difficult and time-consuming task．