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Ozone

by champmag » Sun Jun 05, 2011 9:12 am
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
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by cans » Sun Jun 05, 2011 9:18 am
IMO D
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by jainnikhil02 » Sun Jun 05, 2011 9:49 am
IMO D
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by chilledlife » Sun Jun 05, 2011 10:03 am
champmag 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
has v/s had.
I prefer had appeared immune because it no longer appears immune according to the sentence. Eliminate A, B & C.

Between D & E, I think D is very clear.
D is the answer
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by dubinsky » Mon Jun 06, 2011 1:00 am
had definitely makes more sense in this context than has....

Although option d doesnt well agree well withh the ear neverthless it is the best alternative
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by GMATGuruNY » Tue Jun 07, 2011 5:57 am
champmag 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
In A, B and C, has appeared does not convey the proper sequence of events. Here is the breakdown:
1) The present perfect have realized indicates that sometime in the past we started to realize that emissions deplete the ozone layer.
2) Once we started to realize (in the past) that emissions deplete the ozone layer, the ozone no longer appeared immune.
3) To convey an action completed in the past, we use the past perfect: the ozone had appeared immune, but then it no longer appeared immune.
4) Thus, the following is correct:

The ozone had long appeared immune; we have now realized, though, that emissions deplete the ozone layer.

Eliminate A, B and C.

In E, the repetition of the pronoun it creates confusion: it had long appeared that it was immune. The function of the first it is not immediately clear. E is also needlessly wordy. Eliminate E.

The correct answer is D.

The idiom issue also should be noted:

Immune from means exempt from (as in immune from prosecution).
Immune to means not affected by (as in immune to her beauty).

The correct idiom for the SC above is immune to.
Last edited by GMATGuruNY on Thu Jul 21, 2011 10:22 am, edited 2 times in total.
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by nafiul9090 » Thu Jun 09, 2011 7:34 am
GMATGuruNY wrote:
champmag 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
In A, B and C, has appeared does not convey the proper sequence of events. Here is the breakdown:
1) The present perfect have realized indicates that sometime in the past we started to realize that emissions deplete the ozone layer.
2) Once we started to realize (in the past) that emissions deplete the ozone layer, the ozone no longer appeared immune.
3) Thus, the past perfect is better:

The ozone had long appeared immune; we have now realized, though, that emissions deplete the ozone layer.

Eliminate A, B and C.

In E, the repetition of the pronoun it creates confusion: it had long appeared that it was immune. The function of the first it is not immediately clear. Eliminate E.

The correct answer is D.

The idiom issue also should be noted:

Immune from means exempt from (as in immune from prosecution).
Immune to means not affected by (as in immune to her beauty).

The correct idiom for the SC above is immune to.

hello mitch

just for clarification. as we know that past perfect has some referrent of simple past event. here, is "we have now realized" the implied past event for the correct choice???


regards nafi
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by GMATGuruNY » Thu Jun 09, 2011 8:49 am
nafiul9090 wrote:
GMATGuruNY wrote:
champmag 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
In A, B and C, has appeared does not convey the proper sequence of events. Here is the breakdown:
1) The present perfect have realized indicates that sometime in the past we started to realize that emissions deplete the ozone layer.
2) Once we started to realize (in the past) that emissions deplete the ozone layer, the ozone no longer appeared immune.
3) Thus, the past perfect is better:

The ozone had long appeared immune; we have now realized, though, that emissions deplete the ozone layer.

Eliminate A, B and C.

In E, the repetition of the pronoun it creates confusion: it had long appeared that it was immune. The function of the first it is not immediately clear. Eliminate E.

The correct answer is D.

The idiom issue also should be noted:

Immune from means exempt from (as in immune from prosecution).
Immune to means not affected by (as in immune to her beauty).

The correct idiom for the SC above is immune to.

hello mitch

just for clarification. as we know that past perfect has some referrent of simple past event. here, is "we have now realized" the implied past event for the correct choice???


regards nafi
Yes:

-- have realized implies that we realized -- at some point in the past -- that emissions deplete the ozone layer.
-- had appeared implies that the ozone had appeared immune (at a point further in the past) until we realized (at a more recent point in the past) that emissions deplete the ozone layer.
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by Sharma_Gaurav » Wed Feb 22, 2012 12:38 pm
Tricky sentence.

Agreed that here we already now beleive that ozone is depleted by human influence so we need "had" to say it had appeared immune to human influence.

correct answer is D.
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by dj_vinayak » Thu Sep 13, 2012 6:39 am
GMATGuruNY wrote:
nafiul9090 wrote:
GMATGuruNY wrote:
champmag 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
In A, B and C, has appeared does not convey the proper sequence of events. Here is the breakdown:
1) The present perfect have realized indicates that sometime in the past we started to realize that emissions deplete the ozone layer.
2) Once we started to realize (in the past) that emissions deplete the ozone layer, the ozone no longer appeared immune.
3) Thus, the past perfect is better:

The ozone had long appeared immune; we have now realized, though, that emissions deplete the ozone layer.

Eliminate A, B and C.

In E, the repetition of the pronoun it creates confusion: it had long appeared that it was immune. The function of the first it is not immediately clear. Eliminate E.

The correct answer is D.

The idiom issue also should be noted:

Immune from means exempt from (as in immune from prosecution).
Immune to means not affected by (as in immune to her beauty).

The correct idiom for the SC above is immune to.

hello mitch

just for clarification. as we know that past perfect has some referrent of simple past event. here, is "we have now realized" the implied past event for the correct choice???


regards nafi
Yes:

-- have realized implies that we realized -- at some point in the past -- that emissions deplete the ozone layer.
-- had appeared implies that the ozone had appeared immune (at a point further in the past) until we realized (at a more recent point in the past) that emissions deplete the ozone layer.
Hi
I have a doubt here. When we use HAD (Past perfect) , is not the presence of a Simple past compulsory? If yes which part here represents the simple past?
The rule that I state is Past Perfect = HAD + Past Participle ...

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by Crystal W » Tue May 31, 2016 5:08 pm
GMATGuruNY wrote:
champmag 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
In A, B and C, has appeared does not convey the proper sequence of events. Here is the breakdown:
1) The present perfect have realized indicates that sometime in the past we started to realize that emissions deplete the ozone layer.
2) Once we started to realize (in the past) that emissions deplete the ozone layer, the ozone no longer appeared immune.
3) To convey an action completed in the past, we use the past perfect: the ozone had appeared immune, but then it no longer appeared immune.
4) Thus, the following is correct:

The ozone had long appeared immune; we have now realized, though, that emissions deplete the ozone layer.

Eliminate A, B and C.

In E, the repetition of the pronoun it creates confusion: it had long appeared that it was immune. The function of the first it is not immediately clear. E is also needlessly wordy. Eliminate E.

The correct answer is D.

The idiom issue also should be noted:

Immune from means exempt from (as in immune from prosecution).
Immune to means not affected by (as in immune to her beauty).

The correct idiom for the SC above is immune to.
Thanks for your explanation. I have a quick question. Is that correct appear as being using in choice C?
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by GMATGuruNY » Wed Jun 01, 2016 2:30 am
Crystal W wrote: Thanks for your explanation. I have a quick question. Is that correct appear as being using in choice C?
No.
appear as being is unidiomatic.
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by ngk4mba3236 » Wed Jun 08, 2016 10:02 am
gmatguru,
apart from what you mentioned above, is the following also an error in A and B:

Option B: perfect infinitive to have been implies that this action occurs before the modifying preceding action "has long appeared" -- here, this is nonsensical because the act of being immune and act of appearing occur at the same time.

Option A: similar explanation for A.

thoughts ?

as for the OA: getting confused with use of past perfect (had long appeared) because we use past perfect in case of an earlier past event(had long appeared) between the two sequential past events (while the other past event is in simple past). right ?

if so, then how past perfect(had long appeared) stands good here when the other event is in present perfect(have realized), but NOT in simple past ?
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by GMATGuruNY » Thu Jun 09, 2016 3:09 am
ngk4mba3236 wrote:gmatguru,
apart from what you mentioned above, is the following also an error in A and B:

Option B: perfect infinitive to have been implies that this action occurs before the modifying preceding action "has long appeared" -- here, this is nonsensical because the act of being immune and act of appearing occur at the same time.

Option A: similar explanation for A.
This line of reasoning is valid.
as for the OA: getting confused with use of past perfect (had long appeared) because we use past perfect in case of an earlier past event(had long appeared) between the two sequential past events (while the other past event is in simple past). right ?

if so, then how past perfect(had long appeared) stands good here when the other event is in present perfect(have realized), but NOT in simple past ?
The past perfect serves to express an action completed before another PAST EVENT.
It is not required that this past event be expressed as a simple past tense action.
Here, the past event is a present perfect action -- have realized -- which expresses a PAST ACTION that affects the present.
had long appeared expresses an action COMPLETED before this past event.
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by ngk4mba3236 » Fri Jun 10, 2016 10:33 pm
gmatguru,
I think the correct idiom is appear to be. right ?

but here, appear takes direct object immune -- a clear deviation from the above idiomatic structure.

so, could you please explain this apparent discrepancy on gmat ?
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