A question from our
sentence correction "ask me anything" thread:
ririis wrote:
Hi GMAT Ninja,
Some bat caves, like honeybee hives, have residents that take on different duties such as defending the entrance, acting as sentinels and to sound a warning at the approach of danger, and scouting outside the cave for new food and roosting sites.
(A) acting as sentinels and to sound
(B) acting as sentinels and sounding
(C) to act as sentinels and sound
(D) to act as sentinels and to sound
(E) to act as a sentinel sounding
This question's OA is B. My question is what "sounding" functions as? It can't be the parallelism of "acting" and " scouting" because of 2 "and" preceded "sounding" and "scouting". Therefore it must be a noun and parallel with "sentinels".
Before we get into the weeds with grammar terminology, let's take an intuitive, non-technical look at the words in bold:
Some bat caves, like honeybee hives, have residents that take on different duties such as defending the entrance, acting as sentinels and sounding a warning at the approach of danger, and scouting outside the cave for new food and roosting sites.
All four of these words are doing the same thing, right? Each is a duty that can be taken on by the residents of the bat caves. So as a starting point, it makes sense that they could all be in the same grammatical form, since the residents do all four of those things (defending the entrance, acting as sentinels, sounding a warning, and scouting for food). So even if you don't think about the technicalities of grammar and parallelism at all, you might decide that this seems acceptably parallel, and move on.
If you do want some jargon: all of those four words (defending, acting, sounding, scouting) are gerunds, which is a fancy way of saying that they're "-ing" words that function as nouns. (More on "-ing" words in
this article.)
And it wouldn't make sense for "sentinels" and "sounding" to be parallel to each other: "...
acting as sentinels and
sounding a warning..." If the two words in bold were parallel, then the sentence would be saying that the residents "act as sentinels" (which makes sense) and "act as sounding a warning" (which makes no sense). (More on parallelism in
this video if anybody wants a basic refresher.)
Finally, you might be wondering why the word "and" appears so many times in the correct answer. I don't have a very satisfying answer to that, to be honest. In a sense, "acting as sentinels" and "sounding a warning" are all part of the same duty: "sounding a warning" is part of what the residents must do if they're "acting as sentinels." So those two activities are separated by their own "and", but they're still part of the larger structure of parallelism in the sentence ("defending..., acting and sounding..., scouting...").
I hope this helps!