18.(A) Advertisement: Attention pond owners! Ninety-eight percent of mosquito larvae in a pond die within minutes after the pond has been treated with BTI. Yet BTI is not toxic to fish, birds, animals, plants, or beneficial insects. So by using BTI regularly to destroy their larvae, you can greatly reduce populations of pesky mosquitoes that hatch in your pond, and you can do so without diminishing the populations of fish, frogs, or beneficial insects in and around the pond.
Which one of the following is an assumption on which the argument depends?
(A) The most effective way to control the numbers of mosquitoes in a given area is to destroy the mosquito larvae in that area.
(B) Populations of mosquitoes are not dependent on a single body of water within an area as a place for their larvae to hatch and develop.
(C) There are no insect pests besides mosquitoes that pond owners might want to eliminate from in and around their pond.
(D) The effectiveness of BTI in destroying mosquito larvae in a pond does not require the pond owner’s strict adherence to specific application procedures.（E）
(E) The fish, frogs, and beneficial insects in and around a pond-owner’s pond do not depend on mosquito larvae as an important source of food. My reasoning line:
BIT kill larvae------àreduce mosquitoes+ no diminishing fish population
Assumption:
A : destroy larvae-----àreduce mosquitoes
E: reduce mosquitoes----àno diminishing fish population
Why not A , 如果A取非,原文就不成立了,所以A 应该是assumption 阿!
Pleae read the conclusion carefully : Regular use of BTI can reduce mosquitoes without diminishing the populations of fish, frogs and other beneficial insects
Besides, A is NOT the assumption because: to control the population of mosquitoes, 'the most effective way " does not necessarily mean that people are going to, or should choose it. People may choose less effective treatment in order to avoid side effects.
Therefore, even if you negate A, the argument will not go wild
SO , if I change the most effective way to the only way , will it be assumption?
(A) The only way to control the numbers of mosquitoes in a given area is to destroy the mosquito larvae in that area.
still not a assumption. Carefully read the conclusion: Regular use of BTI can reduce mosquitoes without diminishing the populations of fish, frogs and other beneficial insects
if you negate your assumption: destroy the mosquito larvae is not the only way to control the number of mosquitoes in a given area.
the conclusion is still viable. the conclusion just states that BTI is effective, not the only effective way, so does not need you assumption.
明白了 谢谢
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