大全－Ｂ－17请教ＵＮＬＥＳＳ

17.   Ronald: According to my analysis of the national economy, housing prices should not increase during the next six months unless interest rates drop significantly.

Mark: I disagree. One year ago, when interest rates last fell significantly, housing prices did not increase at all.

It can be inferred from the conversation above that Mark has interpreted Ronald’s statement to mean that

(A) housing prices will rise only if interest rates fall

(B) if interest rates fall, housing prices must rise

(C) interest rates and housing prices tend to rise and fall together

(D) interest rates are the only significant economic factor affecting housing prices（B）

(E) interest rates are likely to fall significantly in the next six months

答案是Ｂ，我的问题是，ＮＯＴ　Ａ　，ＵＮＬＥＳＳ　Ｂ　的关系应该是Ａ－－＞Ｂ吧（这是ＸＤＦ书上写的），也就是ＨＰ的上升推出ＩＲ的下降

ＩＦ　Ａ　ＴＨＥＮ　Ｂ，是Ａ－－＞Ｂ，答案Ｂ也就是ＩＲ下降－－＞ＨＰ上升

１．ＨＰ的上升推出ＩＲ的下降

２．ＩＲ下降－－＞ＨＰ上升　　　　能相等？？？还是我对ＵＮＬＥＳＳ的理解有问题？或者是钻牛角尖？

题目是做对的选的是Ｂ，但是我用关系一推觉得有问题，有点乱。请牛人指教．感觉思路还是比能做题目重要很多。谢谢．

1。你对UNLESS的理解正确（其它充分必要条件指示词见“充分必要条件指示词”：LAWYER）

2。R的意思： housing prices  increase ---->interest rates drop

    M举反对（disagree）R的例子：去年 interest rates  fell ，housing prices did not increase 。

3。M举的例子反对不了R，它只能反对interest rates  fell------>housing prices  increase。也即M实际上误认为R的意思为interest rates  fell------>housing prices  increase。即B

那我也想请教一下，按XDF的书上说

A, UNLESS B 应该为 非A－》B或者， 非B－》A，

那这里是不是可以除了楼上的理解HP升－》IR DROP，还可以说 IR INCREASE->HP DROP 呢？

实际上R的意思正是房价上涨——》利率下降

但M误解了R的意思，误认为：利率下降——》房价上涨，正是B选项

Thanks. I finally got it.

This question asks  what has Mark interpreted Ronald’s statement to mean, not what Ronald mean.

Actually, Ronald's words are not important in this question, but the Mark's interpretation is.

Mark disagrees to a statement. The statement = Mark's interpretation of Ronald's words--> the answer

Therefore, to find this answer, we can just invert Mark's words : "One years ago ..........", and know what Mark disagree to.

  "One years ago,when interest rates last fell significantly,housing prices didn't increase at all."  Mark cited the statement to weaken "if interest rates fall,housing prices must rise" -> Mark's interpretation of Ronald's words.

So, we just need to find what Mark disagrees to. That's the answer.