OG会有错题么？

83. Any medical test will sometimes fail to detect a condition when it is present and indicate that there is one when it is not.

(A) a condition when it is present and indicate that there is one

(B) when a condition is present and indicate that there is one

(C) a condition when it is present and indicate that it is present

(D) when a condition is present and indicate its presence

(E) the presence of a condition when it is there and indicate its presence

Answer to Question 83

Only choice C, the best answer, produces a sentence in which every pronoun it refers clearly and logically to the

noun condition. In choices A and B, the phrase indicate that there . is one does not grammatically fit with

when it is not because it has no referent. Choices B and D are imprecise in saying that a test will fail to detect

when a condition is present, since the issue is the presence and not the timing of the condition. Further, its

presence in D leaves the it in when it is not without a logical referent: it must refer to condition, not presence.

Choice E repeats this error; also, the presence ... when it is there is imprecise and redundant.

这是OG上面的一道题目， 我看着答案，觉得题目好像出错了，C选项应该是 a condition when it is present and indicate that it is  not present才对啊！！ 可是OG好像不应该有这种错误啊！！ 敢情大牛们解围~~~万分感激

Any medical test will sometimes fail to detect a condition when it is present and (省略掉了fail to) indicate that it is present.

任何medical test都会有可能无法查出一个已经出现的condition并且更无法指明它(condition)的出现。两个it同指condition，漂亮的很。你的问题是没有看出来fail to的省略，所以会在后面加上个not。

哦？是这样子的啊？？只是很奇怪你们为什么能够察觉出来，我就看不出来呢~~

不过现在仔细看看还真的是呢~~~