In 1860, the Philological Society launched its effort to create a dictionary more comprehensive than the world had ever seen; although the project
would take more than 60 years to complete, the Oxford English Dictionary had been born.
A. would take more than 60 years to complete, the Oxford English Dictionary had been
B. took more than 60 years to complete, the Oxford English Dictionary was
C. would take more than 60 years to complete, the Oxford English Dictionary was being
D. would take more than 60 years to complete, the Oxford English Dictionary was
E. took more than 60 years to complete, the Oxford English Dictionary was about to be
This sentence is confusing because it feels as if we are moving around between past, present, and future, so here's a simpler way of reading it, with sort of a vertical timeline to keep track of verb tenses:
Before 1860: The world "had [n]ever seen" such a comprehensive dictionary
1860: comprehensive dictionary creation "launched".
1860-1920: it "would take"/"took" 60 years to finish
~1920: The OED "had been"/"was"/"was being"/"was about to be" born
"would take" vs. "took"
At this point in the sentence, the dictionary wasn't finished yet, so we can't say "took" 60 years to finish because that implies that it's already completed-- it has to be "would take", because we're looking forward from the past while we are in the present (strange to think about in real life, but it works in grammar-world).
"had been" vs. "was vs. "was being"
Because the completion of the dictionary was a one-time action that has a definite date ("more than 60 years", so sometime around 1920), we have to say "was". "had been" implies that it happened even before the creation was "launched" in 1860 (the same tense as "a dictionary more comprehensive than the world had ever seen"), which isn't true. "was being" is past progressive, which would mean it wasn't completed just yet, but we know that it's already done.
Answer Choice D is the only one with both "would take" and "was".
This is pretty tricky, so feel free to let me know if you'd like more explanation or have any other questions!
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