FeiFei-64

If the city council institutes new parking regulations, city revenues will surely increase, since studies have conclusively shown that, if such parking regulations are put into effect, there is an increase in parking violations, and an increase in parking violations will result in a greater number of parking fines collected.

 64. If the statements in the passage are true, which one of the following must also be true?

(A) Unless there is an increase in the number of parking violations in the city, city revenues will not increase.

(B) If the city council institutes new parking regulations, the council will fall from favor with the citizens.

(C) The city council will institute new parking regulations only if an increase in city revenues can be expected to result.

(D) If the city council’s new regulations cause more parking violators to be ticketed, the city revenues will increase.

(E) Unless the city institutes a complex system of parking regulations, the city cannot expect traffic violations to increase.

答案选d，想问问a为什么不对。

不是说 not A unless B表达为：A→B

如a选项中，not (city revenues will  increase),unless (an increase in the number of parking violations ),

也就是city revenues will  increase→an increase in the number of parking violations，与原文的一致

i am disagree with you.

which sentence did you get the line of reasoning "city revenues will  increase→an increase in the number of parking violations" from?

according to this argument, "an increase in parking violations will result in a greater number of parking fines collected", an increase in parking violations is cause and a greater number of parking fines collected(city revenues will  increase) is effect, but i can not get any information about which is sufficient condition and which is necessary condition.

there is a controversy between C and D, check some old discuss, you will know better about the relationship between sufficient condition and which is necessary condition.

没明白你说的意思。能说一下我的分析思维错在哪吗？

我对c和d没有疑问。d选项中有complex system，整个就是无关涉及了，完全没考虑。

只是不明白如果按照 not A unless B 可表示为：A→B ，a为什么不对.

NN都过来看看吧！

(A) Unless there is an increase in the number of parking violations in the city, city revenues will not increase.

文章没有提到没有其他方法增加revenue，increase of parking violation可以带来increase of revenue，但是不是必要条件

(B) If the city council institutes new parking regulations, the council will fall from favor with the citizens.

无关选项，文章没有提到favor the citizens

(C) The city council will institute new parking regulations only if an increase in city revenues can be expected to result.

没有提到是为了revenue increase才institute new parking regulations。

(D) If the city council’s new regulations cause more parking violators to be ticketed, the city revenues will increase.

正确

(E) Unless the city institutes a complex system of parking regulations, the city cannot expect traffic violations to increase.

无关选项

明白了，谢谢！