GMAT考试写作指导：Argument范文七三

　　17. This ad recommends non-prescription Acid-Ease over non-prescription Pepticaid

　　for relief of excess stomach acid. The only reason offered is that doctors have written 76

　　million more prescriptions for the full-strength prescription form of Acid-Ease than for

　　full-strength Pepticaid. While this reason is relevant, and provides some grounds for

　　preferring Acid-Ease over Pepticaid, it is insufficient as it stands because it depends on

　　three unwarranted assumptions.

　　The first assumption is that the prescription form of Acid-Ease is more popular

　　among doctors. But this might not be the case, even though doctors have written 76

　　million more prescriptions for Acid-Ease. Acid-Ease may have been available for

　　several more years than Pepticaid; and in the years when both products were available,

　　Pepticaid might have actually been prescribed more often than Acid-Ease.

　　The second assumption is that doctors prefer the prescription form of Acid-Ease

　　for the reason that it is in fact more effective at relieving excess stomach acid. However,

　　doctors may have preferred Acid-Ease for reasons other than its effectiveness. Perhaps

　　Acid-Ease is produced by a larger, more familiar drug company or by one that

　　distributes more free samples. For that matter, the medical community may have simply

　　been mistaken in thinking that Acid-Ease was more effective. In short, the number of

　　prescriptions by itself is not conclusive as to whether one product is actually better than

　　another.

　　The third assumption is that the milder non-prescription forms of Acid-Ease and

　　Pepticaid will be analogous to the full-strength prescription forms of each. But this

　　might not be the case. Suppose for the moment that the greater effectiveness of

　　prescription Acid-Ease has been established; even so, the non-prescription form might

　　not measure up to non-prescription Pepticaid. This fact must be established

　　independently.

　　In conclusion, this ad does not provide enough support for its recommending non-

　　prescription Acid-Ease over non-prescription Pepticaid. To strengthen its argument, the

　　promoter of Acid-Ease would have to show that the comparison between the number

　　of prescriptions is based on the same time period; its effectiveness is the main reason

　　more doctors have prescribed it, and the comparative effectiveness of the two non-

　　prescription forms is analogous to that of the prescription forms.