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Here is a detailed explanation to this question-
nookway wrote:
The widely accepted big-bang theory holds that the universe began in an explosive instant 10 to 20 billion years ago and has been expanding ever since.
(A) that the universe began in an explosive instant 10 to 20 billion years ago and has been expanding
(B) that the universe had begun in an explosive instant 10 to 20 billion years ago and had been expanding
(C) that the beginning of the universe was an explosive instant 10 to 20 billion years ago that has expanded
(D) the beginning of the universe to have been an explosive instant 10 to 20 billion years ago that is expanding
(E) the universe to have begun in an explosive instant 10 to 20 billion years ago and has been expanding
Meaning is crucial to solving this problem:Understanding the intended meaning is key to solving this question; the intended meaning of this sentence is that according to the big-bang theory, the universe began during an explosive instant 10 to 20 billion years ago and has been expanding ever since.
Concepts tested here: Meaning + Tenses + Parallelism + Awkwardness/Redundancy• Any elements linked by a conjunction (“and” in this sentence) must be parallel.
• The simple present continuous tense is used to refer to actions that are currently ongoing and continuous in nature.
• The simple past tense is used to refer to actions that concluded in the past.
• Past perfect continuous tense (marked by the use of helping verb "had/have been") is used when a sentence contains two actions in past and one action is in greater past as well as continuous in nature; the helping verb "had been" is used with the action that is in the greater past and continuous in nature.
• 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 continuous tense (marked by "has/have been") is the correct tense to refer to actions that started in past and continue into the present.
• 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.
A: Correct. This answer choice uses the clause "the universe began in an explosive instant...and has been expanding", conveying the intended meaning - that the beginning of the universe
took place during an explosive instant in time. Further, Option A correctly uses the simple past tense verb "began" to refer to an action that concluded in the past. Moreover, Option A correctly uses the present perfect continuous tense verb "has been expanding" to refer to an action that began in the past and continues into the present. Additionally, Option A maintains parallelism between the active verbs "began" and "has been expanding". Besides, Option A is free of any awkwardness or redundancy.
B: This answer choice incorrectly uses the past perfect continuous tense verb "had been expanding" to refer to an action that began in the past and continues into the present; please remember, the present perfect continuous tense (marked by "has/have been") is the correct tense to refer to actions that started in past and continue into the present, and the past perfect continuous tense (marked by the use of helping verb "had/have been") is used when a sentence contains two actions in past and one action is in greater past as well as continuous in nature; the helping verb "had been" is used with the action that is in the greater past and continuous in nature. Further, Option B incorrectly uses the past perfect tense verb to refer to the sole action in the sentence that concluded in the past; remember, the simple past tense is used to refer to actions that concluded in the past, and 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".
C: This answer choice alters the meaning of the sentence through the clause "the beginning of the universe was an explosive instant...that has expanded"; the construction of this clause illogically suggests that the beginning of the universe
was, itself, an explosive instant in time; the intended meaning is that the beginning of the universe
took place during an explosive instant in time. Further, Option C incorrectly uses the present perfect tense verb "has expanded" to refer to an action that began in the past and continues into the present; remember, the present perfect continuous tense (marked by "has/have been") is the correct tense to refer to actions that started in past and continue into the present, 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.
D: This answer choice alters the meaning of the sentence through the phrase "to have been an explosive instant...that is expanding"; the construction of this phrase illogically suggests that the beginning of the universe
was, itself, an explosive instant in time; the intended meaning is that the beginning of the universe
took place during an explosive instant in time. Further, Option D incorrectly uses the simple present continuous tense verb "is expanding" to refer to an action that began into the past and continues into the present; please remember, the present perfect continuous tense (marked by "has/have been") is the correct tense to refer to actions that started in past and continue into the present, and the simple present continuous tense is used to refer to actions that are currently ongoing and continuous in nature. Additionally, Option D uses the passive voice construction "to have been an explosive instant", leading to awkwardness and redundancy.
E: This answer choice fails to maintain parallelism between the infinitive verb form "to have begun" and the active verb "has been expanding"; please remember, any elements linked by a conjunction ("and" in this sentence) must be parallel. Further, Option E uses the passive voice construction "to have begun", leading to awkwardness and redundancy.
Hence, A is the best answer choice.To understand the concept of "Perfect Continuous Tenses" on GMAT, you may want to watch the following video (~2 minutes):
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 (~2 minutes):
All the best!
Experts' Global Team
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