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题库 / Prep2012-CR-69
Southington University's fund-raisers succeeded in getting donations from 80 percent of the potential donors they contacted this year. This rate would be the expected rate if the only potential donors contacted were those who have donated in the past. But good fund-raisers constantly contact less likely prospects in an effort to expand the donor base. Thus the high success rate, far from showing that the fund-raisers did a good job, shows insufficient canvassing effort.
Which of the following, if true, most seriously weakens the argument?
Among potential donors contacted by Southington University's fund-raisers, the majority of those who did not make donations were people who had made donations to the university in the past.
The amount of money raised by Southington University's fundraisers this year was lower than the amount they had raised in any of the previous several years.
Individual donations made to Southington University this year were, on average, slightly larger than were average individual donations made to many other universities.
Fund-raisers contacting past donors are not only to get new donations but also to get names of potential new donors to contact.
The majority of the donations that fund-raisers succeeded in getting for Southington University were from donors who had never given to the university before.
前提：作者假设：只有联系老人，才能有高成功率
This rate would be the expected rate if the only potential donors contacted were those who have donated in the past.
结论：只联系老人，不联系新人，不是好募捐者
——直接削弱假设：联系了新人，而不是仅联系老人
高成功率→（GAP）仅老人→不是好的募捐者
果因推理
P:（果）高成功率
C.(因)仅联系老人
——他因削弱：联系新人，也会有高成功率
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