GMAT Sentence Correction (SC) | Re: The decline of the mountain yellow-legged frog in the high

josepiusn , it's very dangerous to pull out a few words from a sentence and say that they sound awkward. While this can occasionally help us to find portions with errors, if we can't name an actual error, we should defer judgment and try to find another way to eliminate.

In this case, "could well list" is just fine. "Could well" is just a modifier saying that something very well may happen. In this case, what very well may happen? The service may list the frog as endangered.
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