求助OG10 83

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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

 解释上面说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. 请问是什么意思啊？谢谢大家。

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