如何区分support和assumption，例题29，大家看我的区分对不对

yoyo_jingxuan

assumption和support的区分：尤其是在目的措施型的题目里面，有的时候assumption和support很难区分，我自己就老做错，后来我发现一个规律，assumption的答案是绝对不会出现新元素的，因为措施目的是一个逻辑链，assumption只可以去补足这个逻辑链，但是不能出现旁支去证明这个逻辑链，旁支证明是support，例题：

29.        (30663-!-item-!-188;#058&005676)

To prevent harbor porpoises from getting tangled in its nets and suffocating, a fishing company installed acoustic alarms on all its boats that fish in waters off Massachusetts.  The sound emitted temporarily disorients the porpoises and frightens them away.  Since the installation of the alarms, the average number of porpoises caught in the company's nets has dropped from eight to one per month.  The alarms, therefore, are saving the lives of harbor porpoises in those waters.
BD的选项恰恰就是assumption和support的区别。Assumption是要回答why，为什么能达到这个目的，是因为alarm可以让鱼避免被撞上，D其实应该是support结论，也就是说从eliminate他因加强结论，alarm的确有用，旁支支持

Which of the following is an assumption on which the argument depends?

(A) The use of acoustic alarms increases the number of commercial fish caught by the fishing company's boats.
(B) When disoriented, harbor porpoises are not significantly more likely to be killed by other boats.
(C) Environmentalists advocate the use of acoustic alarms as a means of protecting the harbor porpoise population.
(D) The alarms were installed at the time of year when harbor porpoises are most plentiful in the Massachusetts waters.
(E) The cost of installing acoustic alarms on fishing boats is less than the cost of repairing nets damaged by harbor porpoises.

不知道这样区分是不是正确