OG review 11-85

charlie6989

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

Ans:C
看了討論串關於D的解釋還是不清, OG10:Further, its presence in D leaves the it in when it is not without a logical referent: it must refer to condition, not presence
OG11 the final it has no referent
為何D的it 會無指代呢？？

angela61sata

如果indicate是跟detector并列的话，应该是to indicate，由于没有to，所以导致它跟fail并列，句子成为：will sometimes fail to detect and indicate its presence，这样its就没有指代了，但C中indicate跟detect并列，所以指代明确是condition。而且D中is present和its presence不并列，所以D错

个人理解~