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

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

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31 Aug 2008, 10:54
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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.

(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
[Reveal] Spoiler: OA

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

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01 Sep 2008, 00:34
arorag 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

Not an esay one. First selection is based upon "immune to or from". Immunie TO is right for this case so choices narrowed down to C, D, or E. Out of 3, D is best. Past perfrect tense means any action stopped at past.

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

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01 Sep 2008, 11:05
Immune to is the correct idiom.

Immunity to a disease/virus/bacteria. Immunity from is wrong.

A & B out.

Eliminate C for the evil being.

The non underlined part "we have now realized" is in past tense. So the event that occurs before it needs to be in past perfect.

D & E does that.

E is lengthy, awkward and uses it twice (IMO not needed twice)

D remains.

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

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27 Oct 2008, 15:12
OA is D.

I chose B for this problem because even though I agree that "immune from" is wrong, I had a bigger problem with "had appeared." We don't have 2 verbs that occurred in the past. We only have 1 verb, so I felt that there was no reason to have a past perfect. Would anyone comment on that point?

Thanks

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

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03 Dec 2008, 04:10
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snaps wrote:
tarek99 wrote:
OA is D.

I chose B for this problem because even though I agree that "immune from" is wrong, I had a bigger problem with "had appeared." We don't have 2 verbs that occurred in the past. We only have 1 verb, so I felt that there was no reason to have a past perfect. Would anyone comment on that point?

Thanks

Went with B for exactly the same reason. Would appreciate any input on the subject.

I think I have figured it out. First of all, the second independent clause after the semicolon starts with "we have now realized." We have to realize that "have realized" is a present perfect, meaning that an action started in the past and that this action is still occurring today. So this action started in the past, and the clause before it refers to an event that occured before the last independent clause. I think this should make sense. What do you think?

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

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03 Dec 2008, 16:12
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!

Okie thats lot of crap in the sentence

Ozone.... human influence

Immune to....is correct usage and hence A, B is kicked offf

Being is wordy in GMAT ( however, when you feel answer that you have obtained is not the best, go and recheck ones eliminated on the basis of being) Kick off C

E has wordy too. That doesnt have anything to modify nor demonstrate ( That is a relative pronoun used a restrictive/essential modifer and a demonstrative pronoun -often seen in comparison statement ...to that of...)

Mark D

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

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16 Dec 2008, 14:58
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And what I say is -- Snaps and Tarek, you are both correct.

Whenever I and others say that the perfect tense describes an action that happened in the past and "continues up to the present", we are actually oversimplifying somewhat. The perfect tense usually means this, but it can also mean that the action occurred in the past and CREATED A CONDITION which continues to the present AND is relevant. That is what the perfect means in this case: We realized in the past that emissions deplete the ozone layer -- we are NOT still in the process of realizing -- but now we are in a state of KNOWING this, and it matters.

So the event of realizing is a past event. The appearance that the ozone layer was immune to human interference existed BEFORE that past event. For events or conditions that happened before another past event, we use the pluperfect, "had appeared". This reduces the choice to D and E, and E is unnecessarily wordy.
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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26 Jan 2009, 07:06
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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"

I'll go with D

To answer your question at the last - 'had' is to be used when there are 2 past actions in a sentence. 'Had' is to be placed before the action that is performed earlier than the other one. For ex:- The show "had" started by the time we "arrived".

"HAS" is the present perfect form, which means that the action is still going on...

Coming back to the question : The realization( we realized) says that it is the later action hence the earlier action(" appeared") takes "had". Also, I think, immune to is better than immune from.

So we are left with D & E. D is better than E because it is concise and deletion of "that it was" is not causing any loss in clarity

Correct me if I'm wrong....What is OA?

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

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26 Jan 2009, 08:14
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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"

immune from --> free, exempt (immune from arrest, immune from further taxation)
Immune to --> not susceptible or not responsive ( immune to cancer, immune to all pleas)

here "immune to" correct idiom
A, B are out.

we have now realized --> means they just realized .. this is past tense.
so first setence must be in the past tense. --> "had long appeared" makes sense.

C - out

between D and E

E -- "that it was" --> wordy/redundant.

D is the best.
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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26 Jan 2009, 11:45
I was not aware of "immune from" as the correct idiom. Thanks x2suresh for the info. I selected D for the following reasons.

Since "immune to" is the correct idiom, only C, D and E are remaining options. Among these, D is the most concise.

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

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26 Jan 2009, 20:01
study wrote:
Thanks, unplugged.

Can you explain which is the first action and which is 2nd in the ozone sentence, for 'had' to be used.

The first action : The ozone had long appeared
The second action: We realized........It is only after "the appearance" that we "realized"

I hope it's clear

BTW What is the OA?

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

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23 Jun 2010, 04:34
I chose D, also. You can eliminate A-C because of the use of the present perfect "has". You want past perfect because the ozone has stopped appearing immune to human influence.

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

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23 Jun 2010, 12:48
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A quick note on the idiom:

"Appear to" is an important idiom here!

Ex. He appears to be a good student.

(There is no structure, "appears as".)

"AS BEING" IS ALWAYS INCORRECT!

Now, if the past is involved in the sentence, then use the perfect infinitive: to + have + V3

Ex. Einstein appears to have been a bad student. (Einstein, now dead, is no longer a student.)

Other idioms like "appear to":
seem to, believed to, estimated to, thought to...

(Idioms are taught in the Small Details lesson at gmaxonline!)
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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13 Oct 2010, 13:04
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Come on guys check the Oxford Dictionary for idiom usage:

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

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13 Oct 2010, 13:14
iamcste wrote:
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!

Okie thats lot of crap in the sentence

Ozone.... human influence

Immune to....is correct usage and hence A, B is kicked offf

Being is wordy in GMAT ( however, when you feel answer that you have obtained is not the best, go and recheck ones eliminated on the basis of being) Kick off C

E has wordy too. That doesnt have anything to modify nor demonstrate ( That is a relative pronoun used a restrictive/essential modifer and a demonstrative pronoun -often seen in comparison statement ...to that of...)

Mark D

as a previous post indicates, immune to and immune from are both widely used in english and is accepted by the oxford dictionary. . hence a and B not kicked out.

i would go with B

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

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14 Oct 2010, 01:11
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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.
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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25 Apr 2011, 07:35
sc-idiom-72113.html

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

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02 Dec 2013, 05:21
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.

you are right daagh. the issue stands unresolved. Even people at Manhattan haven't been able to clarify it. http://www.manhattangmat.com/forums/ozo ... -t638.html

Its sad to see a GMAT prep question with such ambiguities. Idiom or not D doesn't make sense at all. Use of past perfect cant be justified.

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

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06 Jan 2014, 23:28
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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?

Striking out prep. phrases and modifiers, we have..
Ozone, a special form of oxygen that screens out harmful ultraviolet rays, reaches high concentrations twelve miles above Earth, where it had long appeared immune to human influence; we have now realized, though, that emissions of industrial chlorofluorocarbons deplete the ozone layer.

Sequencing of the events is as follows.
Ozone appeared immune (1980s)---> scientists conducted some experiments (1990s) (say event X) ---> (1991) as a result of which we realize that cfcs deplete ozone layer.

'had (long) appeared' denotes that the action had happened in the past before an event X (imaginary event that also happened in the past)
'have (now) realized' denotes that the action is the result of event X (hence present perfect)

It is perfectly right to have a past perfect followed by a present prefect in a scenario such as..

Past perfect --> past action --> present perfect denoting the result of the past action)
Here past action is not necessary, because, present perfect is already denoting the result of the past action (implying that a past action had happened)
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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r [#permalink]

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27 Jan 2014, 01:23
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?

As a semicolon is here, we could see this whole sort of thing as TWO part. The second part(after the semicolon) told you that this is the situation NOW, "HAVE NOW REALIZED". Also, the context implied that the first part is the old view, and the second is a recent view. So it will be more reasonable to use a past perfect tense to make a comparison or just make it logically clear.

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Re: Ozone, a special form of oxygen that screens out harmful ultraviolet r   [#permalink] 27 Jan 2014, 01:23

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