[求助]OG10-83

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（C）

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

这道题我用parallelism来做，然后选的E。

请牛人帮我解释一下E为什么不对阿？

非常感谢！！！

好像并非OG上的题。但anyway,请参见：http://forum.chasedream.com/dispbbs.asp?boardID=23&ID=269147&page=1

按照我的想法,E中也可以用it指代condition.

detect the presence of a condition when it(condition) is there and indicate its presence when it (condition) not there.

对仗非常工整啊!

我还是没明白E为什么错.