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沙发
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发表于 2012-3-13 20:32:09
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Answer choice (A) asks if National Laboratories has performed tests on other
machines from Bolter Industries. To apply the Variance Test, we should supply
different and opposing answers to the question posed by the answer choice.
First, try the answer “No.” With this answer, would the fact that National
Laboratories did not perform safety test on other Bolters machines affect the
safety of the Bolter’s hedge trimmer? No—this does not help us evaluate the
safety of the hedge trimmer. What if the answer was “Yes” ? Would the fact that
National Laboratories performed safety tests on other Bolters machines affect
the safety of the Bolter’s hedge trimmer? Not at all. So, regardless of how we
respond to the question posed in answer choice (A), our view of the conclusion
is the same—we do not know whether the claim that the hedge trimmer is safe
is good or bad. According to the Variance Test, if the answer is correct, then
supplying opposite answers should yield different views of the conclusion.
Since our assessment of the conclusion did not change, the Variance Test tells us
that this answer is incorrect.
The question in answer choice (B) is, “How important to the average buyer of a
power hedge is safety of operation?” Again, apply the Variance Test and supply
opposite answers to the question in the answer choice. In this case, try “Very
Important” and “Not Important.” If safety of operation is very important to a
buyer of hedge trimmers, would that affect whether the Bolter’s hedge trimmer
itself is safe? No. Let’s look at the opposite side: if safety of operation is not
important at all to a buyer of hedge trimmers, would that affect whether the
Bolter’s hedge trimmer itself is safe? No. Because our view of the validity of the
conclusion does not change when we consider different responses to the
question posed in answer choice (B), the Variance Test tells us that answer
choice (B) is incorrect.
The question in answer choice (C) is, what were the results of the tests of
Bolter’s hedge trimmer? Using the Variance Test, supply one response that says,
“Bolter’s hedge trimmer failed the safety test.” If this is true, then the conclusion
is unquestionably weakened. Now supply a response that says, “Bolter’s hedge
trimmer passed the safety test.” If this is true, then the conclusion is
strengthened. So, depending on the answer supplied to the question posed in
answer choice (C), our view of the validity of the argument changes: sometimes
we view the conclusion as stronger and other times as weaker. Therefore,
according to the Variance Test, this is the correct answer. In this instance, the
Variance Test reveals the flaw in the argument: the author simply assumed that
being tested means safety is assured. Nowhere in the argument did the author
mention that the hedge trimmer passed the tests, and the Variance Test reveals
this flaw.
In answer choice (D), “Yes” and “No” responses do not change our view of the
argument, and answer choice (D) is incorrect.
In answer choice (E), “Yes” and “No” responses do not change our view of the
argument, and answer choice (E) is incorrect. |
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发表于 2012-3-13 20:30:43
eople should avoid using a certain artificial fat that has been touted as a resource for those whose medical advisers have advised them to reduce their fat intake.Although the artificial fat, which can be used in place of fat in food preparation, has none of the negative health effects of fat, it does have a serious drawback:it absorbs certain essential vitamins, thereby preventing them from being used by the body. 
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