Dear Friends,
Here is a detailed explanation to this question-
arorag 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
Concepts tested here: Tenses + Pronouns + Idioms + Awkwardness/Redundancy• A noun and its derivatives can only have one referent in a particular sentence.
• “immune to” is the idiomatic construction.
• The past perfect tense (marked by the use of helping verb "had") is used when a sentence contains two actions in the past; the helping verb "had" is used with the action in the "greater past".
• The present perfect tense (marked by the use of the helping verb “has/have”) is used to describe events that concluded in the past but continue to affect the present.
• “being” is only to be used when it is part of a noun phrase or represents the passive continuous verb tense; the use of passive continuous must be justified in the context.
A: This answer choice incorrectly uses the present perfect tense verb “has…appeared” to refer to the earlier of two actions that concluded in the past – ozone long appearing immune to human influence and us realizing that emissions of industrial chlorofluorocarbons deplete the ozone layer; remember, the past perfect tense (marked by the use of helping verb "had") is used when a sentence contains two actions in the past; the helping verb "had" is used with the action in the "greater past", and the present perfect tense (marked by the use of the helping verb “has/have”) is used to describe events that concluded in the past but continue to affect the present. Further, Option A incorrectly uses the pronoun “it” both as a placeholder pronoun and to refer to the noun “Ozone”; remember, a noun and its derivatives can only have one referent in a particular sentence. Additionally, Option A incorrectly uses the unidiomatic construction “immune from”; please remember, “immune to” is the idiomatic construction. Besides, Option A uses the needlessly wordy phrase “appeared that it was immune”, leading to awkwardness and redundancy.
B: This answer choice incorrectly uses the present perfect tense verb “has…appeared” to refer to the earlier of two actions that concluded in the past – ozone long appearing immune to human influence and us realizing that emissions of industrial chlorofluorocarbons deplete the ozone layer; remember, the past perfect tense (marked by the use of helping verb "had") is used when a sentence contains two actions in the past; the helping verb "had" is used with the action in the "greater past", and the present perfect tense (marked by the use of the helping verb “has/have”) is used to describe events that concluded in the past but continue to affect the present. Further, Option B incorrectly uses the unidiomatic construction “immune from”; please remember, “immune to” is the idiomatic construction. Additionally, Option B uses the needlessly wordy phrase “appeared to have been immune”, leading to awkwardness and redundancy.
C: This answer choice incorrectly uses the present perfect tense verb “has…appeared” to refer to the earlier of two actions that concluded in the past – ozone long appearing immune to human influence and us realizing that emissions of industrial chlorofluorocarbons deplete the ozone layer; remember, the past perfect tense (marked by the use of helping verb "had") is used when a sentence contains two actions in the past; the helping verb "had" is used with the action in the "greater past", and the present perfect tense (marked by the use of the helping verb “has/have”) is used to describe events that concluded in the past but continue to affect the present. Further, Option C needlessly uses the word "being", leading to awkwardness and redundancy; remember, “being” is only to be used when it is part of a noun phrase or represents the passive continuous verb tense; the use of passive continuous must be justified in the context.
D: Correct. This answer choice correctly uses the past perfect tense verb “had…appeared” to refer to the earlier of two actions that concluded in the past – ozone long appearing immune to human influence and us realizing that emissions of industrial chlorofluorocarbons deplete the ozone layer. Further, Option D correctly uses the pronoun “it” for only one purpose, as a placeholder pronoun. Additionally, Option D uses the idiomatic construction “immune to”. Besides, Option D is free of any awkwardness or redundancy.
E: This answer choice incorrectly uses the pronoun “it” both as a placeholder pronoun and to refer to the noun “Ozone”; remember, a noun and its derivatives can only have one referent in a particular sentence. Further, Option E uses the needlessly wordy phrase “appeared that it was immune”, leading to awkwardness and redundancy.
Hence, D is the best answer choice.To understand the concept of "Past Perfect Tense" on GMAT, you may want to watch the following video (~2 minutes):
To understand the concept of "Present Perfect Tense" on GMAT, you may want to watch the following video (~1 minute):
To understand the use of "Being" on GMAT, you may want to watch the following video (~2 minutes):
All the best!
Experts' Global Team
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