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# Ozone, a special form of oxygen that screens out harmful ultraviolet r

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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29 Jan 2014, 14:09
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TooLong150 wrote:
Very good question. ACE were awkward. I then had to use the "immune to" idiom to pick D over B. I did not understand how to split the answers using the tenses. Can someone explain how the past perfect is used correctly here?

There is some interesting conversations about the perfect tenses in this post . You are starting off correctly with your question by looking at the split of tenses. The GMAT is providing you with a choice between the present and past perfect tenses. Generally speaking, the present perfect tense is used for actions that started in the past but they, or their effects, are still ongoing. The past perfect is used for actions that started in the past but have a definite end. The setup in this problem makes it very clear that the ozone "appearing to be immune" is something that is no longer happening, so you would eliminate the present perfect options.

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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01 Dec 2014, 00:43
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.

I believe option D) is correct for many reasons that are mentioned above. Even the Past Perfect is justified here.

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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09 Jan 2015, 03:10
Ozone reaches high concentrations twelve miles above Earth, where
it has long appeared that it was immune from human influence;
we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.

Immune to: insusceptible (to) or secure (against): immune to inflation.
Immune from: immune from exempt from, free from
Correct use of immune here is "to".
A/B out.

E is out for obvious reason.

Can someone plz explain D.
What I have read in the forums is that past perfect takes simple past with it.And it seems to be is some sort of rule.
e.g. By the time I reached there, he had finished the class.

(A) has long appeared that it was immune from
(B) has long appeared to have been immune from
(C) has long appeared as being immune to
(D) had long appeared immune to
(E) had long appeared that it was immune to
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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09 Jan 2015, 03:44
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Your reflection is correct, totally. However, this is a great example of a gmatprep question in which the rules divert a bit from an accepted standard i.e. past perfect plus simple past.

According to that rule we do not have a correct answer and this is impossible.

As such , the key thing here is to learn how this exam NEEDS a flexible and resilience strategy to approach.

C and D are our answers, no matter what, based on idiom - first strategy we could use.

But C can be eliminated because the use of being (most of the time is wrong on the gmat and it is used correct in an underlined sentece at the beginning of the same) also because the use of being here conveys a sense that the ozone is immune per se and not from CFC.

Sometimes the best answer is NOT the best in an absolute sense in terms of grammar style or construction, though is correct and communicates the best meaning we could have in that moment.

Pick D and move on. That's it

Hope this helps
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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21 Jan 2015, 02:59
TooLong150 wrote:
Very good question. ACE were awkward. I then had to use the "immune to" idiom to pick D over B. I did not understand how to split the answers using the tenses. Can someone explain how the past perfect is used correctly here?

Hey mate, I will try to address your doubt. If you read this piece of sentence " we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer." it is clear that scientists do not believe anymore that the Ozone layer is not contamined by humans. The use of present perfect, which underlines an action's continuation/perpetration/effect to present time is illogical. Using "had long appeared" you can efficiently convey the author's message. Between D and E you are obviously going to chose D, therefore you don't even need to consider the idiom issue discussed above.
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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27 Jan 2015, 15:10
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I was between C and D.

I chose C, even though it sounds a bit awkward. The reason is that "had long appeared immune to" seems to be missing the verb "to be". So, I would have chosen D, if it was phrased as "had long appeared to be immune to".

One question I have is whether C is gramatically incorrect or not (C: has long appeared as being immune to).

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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27 Jan 2015, 20:33
No, "appeared as being" is not correct. Being is frequently used incorrectly (but not always!) so if you are between two options and you don't know how to eliminate, you can guess away from 'being'.
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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29 Jun 2015, 23:14
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Ozone, a special form of oxygen that screens out harmful ultraviolet rays, reaches high concentrations twelve miles above Earth, where it has long appeared that it was immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.

Meaning : Everybody thought that ozone was immune from human influence. But we have now realized that ozone is not immune.

a) has long appeared that it was immune from
As per the sentence, the action of appearing has ended as we have now realized that it is not immune. Hence the action of appearing cannot be present perfect. It has a definite end.

b) has long appeared to have been immune from
As per the sentence, the action of appearing has ended as we have now realized that it is not immune. Hence the action of appearing cannot be present perfect. It has a definite end.

c) has long appeared as being immune to
As per the sentence, the action of appearing has ended as we have now realized that it is not immune. Hence the action of appearing cannot be present perfect. It has a definite end.
And
being immune -> Action of immune is still continuing -> Which is absurd

d) had long appeared immune to

e) had long appeared that it was immune to
instead of "That it was immune" , we can use "immune" which means the same thing.

Doubts:
1) if there is a past perfect why not we have a simple past tense anywhere. We actually have.
Definition of present perfect is "The action happened in the past and either the action or its effect is still continuing when the statement is made".
We have now realized -> We started the process of realizing some time back but may be some experiments are still continuing or some investigation so the "effect" of realizing is not yet completed. Hence we have past tense of "action of realizing". A good question to practice indeed !!.
2) Immune to -> X is immune to Y -> X is already immune to something already.
Immune from -> X is immune from contracting Y (for example). So I guess we need another action if we use from.

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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30 Jun 2015, 06:37
tarek99 wrote:
Ozone, a special form of oxygen that screens out harmful ultraviolet rays, reaches high concentrations twelve miles above Earth, where it has long appeared that it was immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.

a) has long appeared that it was immune from

b) has long appeared to have been immune from

c) has long appeared as being immune to

d) had long appeared immune to

e) had long appeared that it was immune to

First of all, do "immune from" and immune to" exist in English or is it just one of them?

Thanks!

Past Perfect vs. Present Perfect. Before now, we thought that human cannot affect ozone; however, now, we have realized that ...
The former fact, our initial thought was true before now, so it does not include 'now'.
Present perfect can be used for a verb that happens or is true from past to now (including present)
From the above statements, it is clear that we cannot use peresent perfect here: Eliminate A, B, C

Placeholder 'it': the construction in E is much and unnecessarily wordier than that in D, it appeared that ...
I wouldn't say that choice is E grammatically wrong, but it is less preferable to D

in D: appear + adjective cinstruction is fine

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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14 Apr 2016, 08:27
tarek99 wrote:
Ozone, a special form of oxygen that screens out harmful ultraviolet rays, reaches high concentrations twelve miles above Earth, where it has long appeared that it was immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.

a) has long appeared that it was immune from

b) has long appeared to have been immune from

c) has long appeared as being immune to

d) had long appeared immune to

e) had long appeared that it was immune to

First of all, do "immune from" and immune to" exist in English or is it just one of them?

Thanks!

immune to or from is not a concern here...

If we notice we are talking about two events... 1) when the Ozone was immune and 2) when we realized that its not.
Tenses should reflect meaning.
A,B,C are out.
D - correct
E that it was is unnecessary and redundant (it had long appeared - already has it).

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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17 Apr 2016, 06:29
Ozone, a special form of oxygen that screens out harmful ultraviolet rays, reaches high concentrations twelve miles above Earth, where it has long appeared that it was immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.

Meanining analysis (should be priority always) : IC 1 zone reaches high concetration levels at certain height, where it was immune from human influence - strong ozone!!
IC 2: now they've realized emissions deplete ozone - poor ozone!!
So ozone is no longer immune now, it appeared that it was (immune) earlier

a) has long appeared that it was immune from - has long appeared tells us that it appeared in past and still appears, but no this is not the case. out.

b) has long appeared to have been immune from - same error as above. out.

c) has long appeared as being immune to - same error as above. out.

d) had long appeared immune to - simple past tense would have sufficed as theres no other visible past tense verb for ozone for sequencing. rest all seeems ok anyways check next

e) had long appeared that it was immune to - why use that when I can simply say appeared immune to ..as in the above option so not a concise option. out.

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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07 Jul 2016, 01:05
the ozone had appeared not has appeared.

it was considered immune to ,not now.So we need had not has

D and E are contenders.

D is more concise and conveys meaning.

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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07 Jul 2016, 06:46
udaymathapati wrote:
Ozone reaches high concentrations twelve miles above Earth, where it has long appeared that it was immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.
A) has long appeared that it was immune from
B) has long appeared to have been immune from
C) has long appeared as being immune to
D) had long appeared immune to
E) had long appeared that it was immune to

What is the logic to answer? Is immune to idiomatically correct than immune from?

Something was appeared for Ozone, but now we HAVE realized something.

First event happened in past. Hence Present perfect is not required. A, B and C are out.

D) had long appeared immune to Concise and correct choice.

E) had long appeared that it was immune to 'that it was' is unnecessary and wordy.
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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01 Aug 2016, 08:32
study wrote:
Ozone reaches high concentrations twelve miles above Earth, where it has long appeared that it was immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.

A) has long appeared that it was immune from

B) has long appeared to have been immune from

C) has long appeared as being immune to

D) had long appeared immune to

E) had long appeared that it was immune to

can someone explain the verb tense mood in the sentence - "had vs. has"

Can someone explain why option 'E' is incorrect (apart from "that it was" redundant or option D is more concise than E)
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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01 Aug 2016, 09:55
sairam595 wrote:
study wrote:
Ozone reaches high concentrations twelve miles above Earth, where it has long appeared that it was immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.

A) has long appeared that it was immune from

B) has long appeared to have been immune from

C) has long appeared as being immune to

D) had long appeared immune to

E) had long appeared that it was immune to

can someone explain the verb tense mood in the sentence - "had vs. has"

Can someone explain why option 'E' is incorrect (apart from "that it was" redundant or option D is more concise than E)

in option E, we have pronoun ambiguity error. "that it was immune to", here we don't know if "it" is referring to Earth or Ozone.
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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01 Aug 2016, 10:07
abhimahna wrote:
sairam595 wrote:
study wrote:
Ozone reaches high concentrations twelve miles above Earth, where it has long appeared that it was immune from human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.

A) has long appeared that it was immune from

B) has long appeared to have been immune from

C) has long appeared as being immune to

D) had long appeared immune to

E) had long appeared that it was immune to

can someone explain the verb tense mood in the sentence - "had vs. has"

Can someone explain why option 'E' is incorrect (apart from "that it was" redundant or option D is more concise than E)

in option E, we have pronoun ambiguity error. "that it was immune to", here we don't know if "it" is referring to Earth or Ozone.

the first 'it' in "where it has long appeared " refers to ozone, so can we say the second 'it' also refers to ozone
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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01 Aug 2016, 10:11
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sairam595 wrote:
abhimahna wrote:
sairam595 wrote:

Can someone explain why option 'E' is incorrect (apart from "that it was" redundant or option D is more concise than E)

in option E, we have pronoun ambiguity error. "that it was immune to", here we don't know if "it" is referring to Earth or Ozone.

the first 'it' in "where it has long appeared " refers to ozone, so can we say the second 'it' also refers to ozone

No. The first 'it' is not referring to Ozone. here, 'It' is used to present a fact. I know there are so many 'it's but we need to understand the meaning of the sentence to come to a conclusion.
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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01 Aug 2016, 10:16
Can someone explain why option 'E' is incorrect (apart from "that it was" redundant or option D is more concise than E)

in option E, we have pronoun ambiguity error. "that it was immune to", here we don't know if "it" is referring to Earth or Ozone.

the first 'it' in "where it has long appeared " refers to ozone, so can we say the second 'it' also refers to ozone

No. The first 'it' is not referring to Ozone. here, 'It' is used to present a fact. I know there are so many 'it's but we need to understand the meaning of the sentence to come to a conclusion.

abhimahna,
you mean first 'it' is a placeholder!

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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02 Aug 2016, 05:05
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shonakshi wrote:
I am a little confused here between option D and E, is it not correct that appear is followed by THAT ?This is there in option E

Hi shonakshi ,
In option E , "that it was" is redundant . Also if you notice , there is another if in the sentence that is not in underlined part .

"the repetition of "it" in choice (e) is also highly undesirable. technically, this is not 100% wrong; the first "it" is of a special kind that doesn't require an antecedent. however, that construction is usually used only when there is NOT another "it" in the sentence to muddle things up " -Ron

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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05 Aug 2016, 22:41
"immune to " is correct idiom in this context

Not subject to an obligation imposed on others; exempt: immune from being eliminated in a contest.
Not affected by a given influence; unresponsive: immune to persuasion.

we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer. => to convey meaning of this we need to show past perfect tense in "where it has long appeared that it was immune from human influence"

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r   [#permalink] 05 Aug 2016, 22:41

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