例1. The use of nets at beach resorts to protect swimming areas from sharks has been criticized by environmentalists because the nets needlessly kill thousands of marine animals annually. However, environmentalists have recently discovered that an electrified cable buried beneath the periphery of swimming areas causes sharks to swim away while harming neither humans nor marine life. Hence, by installing such cables, resort communities will be able to maintain tourism while satisfying environmentalists’ concerns.
The statement concerning what the environmentalists recently discovered plays which of the following roles in the argument?
A. A premise of the argument
B. The conclusion of a key term in the argument
C. A clarification of a key term in the argument
D. A reiteration of the conclusion for the sake of emphasis
E. A statement of the position that is being argued against
题目解析：先通过关联词把握文章整体骨架，hence 引导文章结论，最后一句话是文章总结论，那么之前的内容是文章的premise，所以黑体字部分的作用可以确定，是premise of the argument. A是正确答案。
英文标志词：boldface, play roles.
例2 . Hunter: Hunters alone are blamed for the decline in Greenrock National Forest’s deer population over the past ten years. Yet clearly, black bears have also played an important role in this decline. In the past ten years, the forest’s protected black bear population has risen sharply, and examination of black bears found dead in the forest during the deer hunting season showed that a number of them had recently fed on deer.
The statement in bold plays which of the following roles in the argument?
A. It is the main conclusion of the argument.
B. It is an objection that has been raised against the main conclusion.
C. It is a judgment that the argument opposes.
D. It is a finding that the argument seeks to explain.
E. It provides evidence in support of the main conclusion of the argument.