单项选择题
A．Demand for operator-assisted calls is increasing dramatically.
B．The new electronic operator system, though it has been tested, is expected to require significant adjustments before it can become fully operational.
C．The operators union would be quick to strike the companies involved if operators were dismissed during the current contract period.
D．In one regional trial of the electronic system, virtually all consumers, given a choice, preferred a human operator to an electronic one.
E．The new electronic operator system will complete operator-assisted calls twice as fast as human operator can.
单项选择题 Currently, the number of first-time admissions of individuals diagnosed as manic-depressives to hospitals in Great Britain exceeds by nine times the number of admissions of such patients to public and private hospitals in the United States, even though the population size of the United States is many times that of Great Britain. Which of the following, if true, would be most useful to an attempt to explain the situation described above ？（）
单项选择题 A new ordinance passed by the Gorenton Council a year ago banned the sale of all nonrecyclable plastic packaging for food being sold in Gorenton. A substantial percentage of Gorenton’s plastic waste, however, is still composed of nonrecyclable plastic food packaging. Which of the following, if true, best contributes to reconciling the apparent discrepancy above ？（）
单项选择题 Stone Age potters crafted complicated and often delicate ceramic pots, tools, and jewelry. They also crafted crude pottery figurines. Many of the delicate ceramic pots, tools, and jewelry have been found intact or nearly so, whereas the figurines, crafted at roughly the same time as the ceramics, have largely been found in tiny fragments. Which of the following, if true, best explains why few of the pottery figurines, but many of the delicate ceramics, have been found intact ？（）