Dear Friends,
Here is a detailed explanation to this question-
jerrywu wrote:
Over the course of the eighteenth century, the average output of ironwork tripled as a result of several improvements in blowing machinery and because coal replaced charcoal as the fuel used in the smelting of iron ore.
A. Over the course of the eighteenth century, the average output of ironwork tripled as a result of several improvements in blowing machinery and because coal replaced charcoal as the fuel used in the smelting of iron ore.
B. Over the course of the eighteenth century a tripling in the average output of ironwork was due to the replacement of charcoal by coal for the fuel used in the smelting of iron ore, in addition to several improvements in blowing machinery.
C. With charcoal's being replaced by coal as the fuel used in the smelting of iron ore and several improvements in blowing machinery, the average output of ironwork tripled over the eighteenth century.
D. The replacement of charcoal with coal for the fuel used in the smelting of iron ore and several improvements in blowing machinery, the average output of ironwork tripled over the eighteenth century.
E. Charcoal being replaced by coal as the fuel used in the smelting of iron ore, and several improvements in blowing machinery, which tripled the average output of ironwork over the course of the eighteenth century.
Concepts tested here: Comparisons + Parallelism + Idioms + Awkwardness/Redundancy• “like” is used for comparing nouns, “as” is used for comparing actions/clauses, and “such as” is used for giving examples.
• All elements in a list must be parallel.
• “as A as B” is a correct, idiomatic usage.
A: This answer choice incorrectly uses “like” to provide the examples of “tar sands”, “heavy oil”, and “shale”; remember, “like” is used for comparing nouns, “as” is used for comparing actions/clauses, and “such as” is used for giving examples. Further, Option A fails to maintain parallelism among “tar sands”, “heavy oil”, and “in shale”; remember, all elements in a list must be parallel. Additionally, Option A incorrectly uses the unidiomatic construction “as A than B”; remember, “as A as B” is a correct, idiomatic usage.
B: This answer choice incorrectly uses “like” to provide the examples of “tar sands”, “heavy oil”, and “shale”; remember, “like” is used for comparing nouns, “as” is used for comparing actions/clauses, and “such as” is used for giving examples. Further, Option B fails to maintain parallelism among “tar sands”, “heavy oil”, and “in shale”; remember, all elements in a list must be parallel. Additionally, Option B incorrectly uses the unidiomatic construction “as A than B”; remember, “as A as B” is a correct, idiomatic usage. Besides, Option B uses the needlessly wordy phrase “than are”, leading to awkwardness and redundancy.
C: This answer choice fails to maintain parallelism among “tar sands”, “heavy oil”, and “in shale”; remember, all elements in a list must be parallel. Further, Option C uses the needlessly wordy phrase “as are”, leading to awkwardness and redundancy.
D: Correct. This answer choice correctly uses “such…as” to provide the examples - “tar sands”, “heavy oil”, and “shale”. Further, Option D maintains parallelism among “tar sands”, “heavy oil”, and “shale”. Additionally, Option D correctly uses the idiomatic construction “as A as B”. Besides, Option D is free of any awkwardness or redundancy.
E: This answer choice incorrectly uses the unidiomatic construction “as A than B”; remember, “as A as B” is a correct, idiomatic usage.
Hence, D is the best answer choice.To understand the concept of "Like" vs "As" on GMAT, you may want to watch the following video (~2 minutes):
All the best!
Experts' Global Team
_________________