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

如果把结尾when it is not改成when there is not，是否A就正确了呢？？

That is:

A condition when it is present and indicate that there is one when there is not.

一般英语里面应该没有问题。

但是，如果放在GMAT里面，还是错误。通过there be基本上可以宣布其死刑。

所以学习OG在于学习ETS的思路.