750Barrier wrote:
daagh wrote:
IMO, - immune from - is as acceptable as - immune to.-
E. g: Having suffered typhoid a couple of times, Tom is now immune to that disease.
You are immune from contracting sexually transmitted diseases, when you employ safe sex practices (meaning that you are protected from the ill effects of something, when you are immune from them.)
So what decides the use of - to or from - is the context. I would in the given context choose -immune from - rather than - immune to -because the meaning implies that ozone is far placed and hence protected from human influence.
What however baffles me is how we can afford a past perfect here, when the thumb rules state that
1. A past perfect can not remain alone without a simple past.
2. By custom, a past perfect can not be joined with a present tense or a present perfect, without a past tense intervening.
I can not digest choice D and E, unless somebody makes bold to say that the use of past perfect here is an exception under some blah, blah rule.
B on the other hand uses the present perfect tenses for all descriptions - has long appeared to - and -have been immune from - and it goes parallel with the present perfect in non-underlined part - we have now realized -
B for me therefore on my own reckoning.
Dear
GMATNinja - i have had the same understanding and chose B over D. Will u please help to clarify?
As described by
EducationAisle in
this post, it comes down to meaning:
- People now understand that the ozone is NOT immune from human influence (they've realized that humans' emissions of industrial chlorofluorocarbons deplete the ozone layer).
- But in the past, the ozone appeared to be immune from human influence.
- So at SOME point in the past, a realization was made and things changed: people went from (1) thinking the ozone was immune from human influence to (2) understanding that the ozone is NOT immune from human influence.
- We want our sentence (and the verb tenses) to clearly reflect that change.
Here's a slightly modified/simplified version of (B):
Quote:
{Ozone} has long appeared to have been immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.
Notice that "has appeared" and "have realized" use the same tense (present perfect). As a result, it seems as though these two actions are happening at the same time -- but that doesn't make any sense. Once people realized that emissions were depleting the ozone layer, they stopped thinking the ozone was immune from human influence (the ozone
no longer appeared to be immune). Also note that the timing of "have been immune" in relation to "has appeared" is unclear in (B).
The past perfect in (D) expresses the logical timeline more clearly: the realization has
already occurred, and the "appearing" happened at some point further in the past than the realization.
And if you're thinking, "Wait, how can we use "have realized" for something that already occurred?", consider these examples:
"Since 2015, Tim has lived in Los Angeles, Breckenridge, and Queens."
Does this mean Tim started living in all three of those places in 2015 and that he still lives in all three of those places now? Of course not! It means that he's lived in each of those places
between 2015 and now.
"Tim has decided to quit his job."
Does this mean that Tim started deciding at some point in the past and is still in the process of deciding? Not exactly. The verb tense implies that the action happened at some
unspecified time in the recent past.
As explained in
this post, when you want to indicate a
specific time frame in the past, a simple past verb makes sense. But if you only want to communicate that it happened at some
unknown time in the past, present perfect can be acceptable, too.
I hope that helps!
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08 Dec 2021, 09:10
