[求助]大全-15-13, 大全-15-15的阅读问题

大全-15-13.     Biometric access-control systems—those using fingerprints, voiceprints, etc., to regulate admittance to restricted areas—work by degrees of similarity, not by identity. After all, even the same finger will rarely leave exactly identical prints. Such systems can be adjusted to minimize refusals of access to legitimate access-seekers. Such adjustments, however, increase the likelihood of admitting impostors.

Which of the following conclusions is most strongly supported by the information above?

(A) If a biometric access-control system were made to work by identity, it would not produce any correct admittance decisions.

(B) If a biometric access-control system reliably prevents impostors from being admitted, it will sometimes turn away legitimate access-seekers.

(C) Biometric access-control systems are appropriate only in situations in which admittance of impostors is less of a problem than is mistaken refusal of access.

(D) Nonbiometric access-control systems—based, for example, on numerical codes—are less likely than biometric ones to admit impostors.（B）

(E) Anyone choosing an access-control system should base the choice solely on the ratio of false refusals to false admittances.

请教13题C选项为什么不对啊？偶用了排除法，最后剩下B和C。谢谢

１３题目的意思是这样的，说有一个系统（认人用的）它的原理是检验相似度（比如你手掌有１００个横纹）而不是通过特性来判定～！但是毕竟（ＥＴＳ总要转折的，呵呵｀！）同一个手指有的时候也会留下不同的印记．

所以我们是可以减小这种误差的．（就是说更少的依赖相似度）．那么就会给那些ＩＭＰＯＳＴＯＲ们有可乘之机了．（因为他们就是靠ＳＩＭＩＬＡＲＩＴＹ的）

Ｃ有些主观，文中没有说什么情况之下很ＡＰＰＲＯＰＲＩＡＴＥ．

(C) Biometric access-control systems are appropriate only in situations in which admittance of impostors is less of a problem than is mistaken refusal of access.

from the passage, BCC systems will have problems of refusal of access, but since it is used to prevent impostors, it's okay, so C is wrong b/c the systems might be more appropriate in situations mistaken is less a problem..

the only word here 太絕對了

请问一下c怎么翻译啊，看不太懂的说

Biometric access-control systems are appropriate only in situations in which admittance of impostors is less of a problem than is mistaken refusal of access.

C：BBC只适用于“让错误的人（impostors）进入”的问题严重性不如“拒绝正确的人（真正的指纹主人）进入”严重时。简单说就是应用于更需要减少错误refusal的场合。感觉这种类型的回答曾经出现在正确答案中，不过想不起来具体哪题了……

这里C的only确实有点绝对化了，但是个人也想不出反例。5楼的解释没看懂。。。有谁能再解释一下呢？

顺便问下，B是属于逆否命题吧

试着解释一下：

Such systems can be adjusted to minimize refusals of access to legitimate access-seekers. Such adjistments, however, increase the likelihood of admitting impostors.
=minimize refusals of access to legitimate access-seekers--〉increase the likelihood of admitting impostors.
逆否命题decrease the likelihood of admitting impostors.--〉maximize refusals of access to legitimate access-seekers.与b吻合。

(B) If a biometric access-control system reliably prevents impostors from being admitted, it will sometimes turn away legitimate access-seekers.

又仔细看了下题，13题排除C的关键在于Such systems can be adjusted to minimize refusals of access to legitimate access-seekers. Such adjistments, however, increase the likelihood of admitting impostors.这句

前面说After all, even the same finger will rearely leave exactly identical prints.暗示的意思是这样会拒绝很多legitimate。所以可以adjust一下，但adjust的新问题是。。。

C说BBC只适用于situations in which admittance of impostors is less of a problem than is mistaken refusal of access.简单说就是应用于更需要减少错误refusal的场合。其实这是指adjust后的情况。如果让impostors进入是更不能忍受的错误的话，只要像一开始那样，不要adjust就行了。

楼上的姐姐想多了吧，

C错就错在讨论 合适性上，而此话题文中从未涉及！