31:

Political Advertisement:

Mayor Delmont’s critics complain about the jobs that were lost in the city under Delmont’s leadership.  Yet the fact is that not only were more jobs created than were eliminated, but each year since Delmont took office the average pay for the new jobs created has been higher than that year’s average pay for jobs citywide.  So it stands to reason that throughout Delmont’s tenure the average paycheck in this city has been getting steadily bigger.

Which of the following, if true, most seriously weakens the argument in the advertisement?

1. The unemployment rate in the city is higher today than it was when Mayor Delmont took office.
2. The average pay for jobs in the city was at a ten-year low when Mayor Delmont took office.
3. Each year during Mayor Delmont’s tenure, the average pay for jobs that were eliminated has been higher than the average pay for jobs citywide.
4. Most of the jobs eliminated during Mayor Delmont’s tenure were in declining industries.
5. The average pay for jobs in the city is currently lower than it is for jobs in the suburbs surrounding the city。

选C呢还是D?

NN指教

C is an obvious answer. For if the average pay for jobs that were eliminated has been higher than the average pay for jobs citywide,  the average pay citywide will not be better than before.

D is not related.

D is not related.

The situation:

The jobs created was more than those eliminated è total number of jobs increased

Average pay for new jobs was higher than total average pay citywide

Conclusion：

The average pay check in the city is increasing.

简单的说就是：新创造的工作薪水高于现在城市平均水平，所以现在城市平均水平高于过去城市平均水平。

翻译过来以后，很明显，结论中比较的范围与前提中比较的范围不一致。前提是现在的局部与现在的整体比较，结论是现在的整体与过去的整体比较。

用数学来分析吧。

过去：城市平均工资A1＝ 将要被eliminate的那部分 E ＋没有被eliminate的那部分 C (C for constant)

现在：城市平均工资A2 = C ＋ 创造的新工作的那部分 N (N for new)

前提说N > A2, 结论说A2 > A1.

要削弱结论，就要说明A2 < A1.由上面的两个式子看出，要想A2 < A1, 就要使 N < E，正是C所说的内容。

1. 原文没有把失业率作为卖点，所以失业率不是削弱的突破口。
2. 当这个人上任的时候，城市工资是十年来最低，有什么关心呢？结论说他上任后每年都往上涨。所以不是削弱。

D.       减少的工作岗位都是在那些走下坡路的行业。这没有提到那些行业的工资情况，所以不能削弱“城市平均工资水平上涨”的结论。反而有可能支持结论，如果假设“走下坡路的行业工资低于城市平均工资水平”成立的话。

E.   现在城市工资水平比乡村工资水平低，无关比较。

Pros: the average pay for the new jobs created has been higher than that year’s average pay for jobs citywide. 

Cons: the average pay for jobs that were eliminated has been higher than the average pay for jobs citywide.

First, the difference betweenthe number of job created and eliminated is not a relavant factor, since it does not directly affects the moving average, neither does the ten year low is relavant, since the argument is not about whether has the economic improved recently.

Second, only the encounter average force is a relavant topic here.

Third, the counter force can weaken the argument, but it can not determine the final outcome, which is determined by both of their relative difference compare to priviouse year's average, difference weighted by the size of each group.

Remember, both group has higher average than the priviouse year's citywide salary, byt it has provide a clue for determining, which group plays a large role in the outcome. Also, the size of each group should be taken into consideration.

In conclusion, the counter argument simply provide some level of encounter force to pressure the origninal claim from Pro side.

推理过程：

条件

1).more jobs created than were eliminated

2). the average pay for the new jobs created has been higher than that year’s average pay for jobs citywide. 

结论： the average paycheck(工资)in this city has been getting steadily bigger.

Weaken, so the average paycheck in fact is the same or less

The average paycheck= total paycheck\ the quantity of jobs

Total paycheck now= total new job paycheck+ total remained job paycheck

Total paycheck past= total eliminated paycheck+ total remained job paycheck

所以现在的total paycheck相比过去是否提高，主要是比较 total new job paycheck- total eliminated paycheck

C 选项说明 有可能total paycheck下降，尽管the quantity of job now是上升，但是the average paycheck 是有可能不变或者下降的。