Dear Friends,
Here is a detailed explanation to this question-
mikeCoolBoy wrote:
Before scientists learned how to make a synthetic growth hormone, removing it painstakingly in small amounts from the pituitary glands of human cadavers.
(A) scientists learned how to make a synthetic growth hormone, removing it painstakingly
(B) scientists had learned about making a synthetic growth hormone, they had to remove it painstakingly
(C) scientists learned how to synthesize the growth hormone, it had to be painstakingly removed
(D) learning how to make a synthetic growth hormone, scientists had to remove it painstakingly
(E) learning how to synthesize the growth hormone, it had to be painstakingly removed by scientists
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 before scientists learned how to synthesize the growth hormone, the only way to procure the hormone was to painstakingly remove it in small amounts from the pituitary glands of human cadavers.
Concepts tested here: Meaning + Modifiers + Tenses + Verb Forms• In a “phrase + comma + noun” construction, the phrase must correctly modify the noun; this is one of the most frequently tested concepts on GMAT sentence correction.
• If a sentence contains multiple past actions, the past perfect tense (marked by the use of the helping verb “had”) is used to refer to all but the most recent action; the simple past tense is used to refer to the most recent action.
A:1/ This answer choice fails to form a complete sentence; as "learned" is part of a modifying phrase, and "removing" is a present participle ("verb+ing"), there is no active verb to act upon the subject pronoun "it".
B:1/ This answer choice alters the meaning of the sentence through the phrases "learned about making a synthetic growth hormone" and the clause "they had to remove"; the construction of these phrases incorrectly implies that before scientists learned that
it is possible to synthesize the growth hormone,
the scientists themselves had to extract the hormone in small amounts from cadavers; the intended meaning is that before scientists learned
how to synthesize the growth hormone,
the only way to procure the hormone was to painstakingly remove it in small amounts from the pituitary glands of human cadavers.
2/ Option B incorrectly uses the past perfect tense verb "had learned" to refer to the later of two actions that concluded in the past - scientists learning how to synthesize the growth hormone and the growth hormone having to be painstakingly removed in small amounts from the pituitary glands of human cadavers; remember, if a sentence contains multiple past actions, the past perfect tense (marked by the use of the helping verb “had”) is used to refer to all but the most recent action; the simple past tense is used to refer to the most recent action.
C: Correct.1/ This answer choice acts upon the subject pronoun "it" with the active verb "had to be...removed" to form a complete thought, producing a complete sentence.
2/ Option C uses the phrase "scientists learned how to synthesize" and the clause "it had to be painstakingly removed", conveying the intended meaning - that before
scientists learned
how to synthesize the growth hormone,
the only way to procure the hormone was to painstakingly remove it in small amounts from the pituitary glands of human cadavers.
3/ Option C correctly uses the simple past tense verb "learned" to refer to the later of two actions that concluded in the past - scientists learning how to synthesize the growth hormone and the growth hormone having to be painstakingly removed in small amounts from the pituitary glands of human cadavers.
D: Trap.
1/ This answer choice alters the meaning of the sentence through the clause "scientists had to remove it"; the construction of this clause incorrectly implies that
the scientists themselves had to extract the hormone in small amounts from cadavers; the intended meaning is that
the only way to procure the hormone was to painstakingly remove it in small amounts from the pituitary glands of human cadavers.
E:1/ This answer choice incorrectly uses "Before learning how to synthesize the growth hormone" to modify the pronoun "it", which refers to "the growth hormone", illogically implying that
the growth hormone learned how to synthesize itself; the intended meaning is that
scientists learned how to synthesize the growth hormone; remember, in a “phrase + comma + noun” construction, the phrase must correctly modify the noun.
2/ Option E alters the meaning of the sentence through the phrase "removed by scientists", incorrectly implying that
the scientists themselves had to extract the hormone in small amounts from cadavers; the intended meaning is that
the only way to procure the hormone was to painstakingly remove it in small amounts from the pituitary glands of human cadavers.
Hence, C is the best answer choice.To understand the concept of "Phrase Comma Subject" and "Subject Comma Phrase" on GMAT, you may want to watch the following video (~1 minute):
To understand the concept of "Past Perfect Tense" on GMAT, you may want to watch the following video (~2 minutes):
All the best!
Experts' Global Team
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