This question is testing the verb tense and idiom.

Verb Tense - You use the past pretense because the sentence is structured like "then and now." first half of the sentence describes how the ozone appeared in the past and latter half of the sentence describes the ozone now.

Idiom - As for the idiom usage...hard to explain but normal English is always "immune to" ....read it aloud and you'll see the "to" is more natural to hear than "from"

sorry but hope my explanation helps!

Hi folks,

Technically we use past perfect to indicate the first out of two events that happened in the past.

Then why is the OA D here.

This is a GMATPrep question.

Please shed light.

Cheers

sumitkhurana wrote:Hi folks,

Technically we use past perfect to indicate the first out of two events that happened in the past.

Then why is the OA D here.

This is a GMATPrep question.

Please shed light.

Cheers

IMO

Ozone...........we "have"....now realised...

so there must be something happened before this. so we need to use simple past tense or past perfect. It leaves us with "D" and "E" only.

BTW although "D" looks better....but what is the exact reason for kicking out "E".....is it because of
i) wordiness
ii) ambiguous "it"
iii) or some grammar rule is broken in "E" ?

Correct answer:

(D) had long appeared immune to

Can someone please explain why it is not necessary to put "to be" after "appeared", i.e., "had long appeared to be immune to."

Thanks.

As for me, I picked "B". I'm mortified!

I think all wrong answers can be eliminated with the correct idiomatic use of "To appear"

In speech we often say "appear to be". This is redundant and incorrect. Instead, on the GMAT it's correct idom is "appear (nothing)".

This idiom error is similar to "consider" idiom. In speech we often say "Linda is considered to be a great artist" but it's incorrect. Instead "Linda is considered a great artist" is correct.

The only answer that correctly uses "appear (nothing)" is E

We can also use verb tense to eliminate A through C. The past perfect "had appeared" is better than the present perfect "has appeared" because the second half of the sentence (we hav now...) demonstrate that the first is in the past.

Why past perfect instead of simple past? Well, the use of present perfect "have discovered" indicates that the discovery has already been made (ie the actual discovery is in the past). To demonstrate that of two past action, one happened earlier, the earlier action must be in the past perfect. In this case, "to appear" happened in the past, but before the discovery, which is also in the past. Thefore , "to appear" is expressed in the past perfect tense "had appeared"

Can you please tell how will you choose between "D" and "E" if we do not remember "appear" idiom ?

appear idiom is the only thing distinguishing D from E. You could argue that the right answer is more concise, but that's just because the correct idiom is shorter than the incorrect one.

TedCornell wrote:appear idiom is the only thing distinguishing D from E. You could argue that the right answer is more concise, but that's just because the correct idiom is shorter than the incorrect one.

Come on, guys, pls refer to Oxford dictionary first:

immune /{speaker}Imju:n/ adjective [notusuallybeforenoun]
1 ~ (to sth) that cannot catch or be affected by a particular disease or illness:
Adults are often immune to German measles.
2 ~ (to sth) not affected by sth:
You'll eventually become immune to criticism. * Few men are immune to her charms. * Our business is far from immune to economic conditions.
3 ~ (from sth) protected from sth and therefore able to avoid it
SYNEXEMPT:
No one should be immune from prosecution.