Dirt roads may evoke the bucolic simplicity of another century, but financially strained townships point out that dirt roads cost twice as much as maintaining paved roads.

(C) maintaining dirt roads costs twice as much as paved roads do.
In this option if we change do to does then whether this will be correct?

Hi GAURAV1113, that will make option C worse than it already is! Since paved roads is plural, we need a plural verb do and not a singular verb does.

I understand paved roads is Plural but as per my understanding maintaining paved roads will need singular verb does, My question was why we cannot extend "maintaining" to paved roads, It is allowed as per ellipsis.?

Ok I understand your point Gaurav. So, if the verb is do, it is obviously clear that paved roads is the subject, while if the verb is does, then we interpret that since paved roads is plural, we need to imply that the word maintaining is elided, so that the verb matches with maintaining.

While it might be a tough ask to codify the exact rules here, in comparison questions, it often comes down to choosing the best of the available options; in B, since do very clear stands for cost to maintain, I would still prefer B.

This is all about being supremely literal with comparisons, as we'll discuss in this week’s YouTube webinar. And I don't think that anybody really loves comparisons, so… I dunno, try to enjoy this one anyway.


This is literally saying that dirt roads themselves cost more than maintaining paved roads. That doesn’t work: we either need to compare “maintaining dirt roads” to “maintaining paved roads” or we can compare the two types of roads. But (A) makes no sense in its current form.


This sounds pretty good! The key here is that the word “do” can replace a verb phrase – and in this case, “do” replaces “cost… to maintain.” So this is saying that “dirt roads cost twice as much to maintain as paved roads [cost to maintain].” Great, that makes sense. Let’s keep (B).

Nope, that wouldn't work. "Maintaining" is a noun in this case (a gerund, if you like jargon; for more on "-ing" words, check out this article), and we'd need to compare the noun "maintaining" to some other noun in terms of its cost. Logically, we can't compare "maintaining" to "dirt roads," and that's exactly what happens in your version of the sentence.

The word "does" can replace some other verb, but "maintaining" isn't a verb here. "Does" would appear to replace "costs", I guess -- so we would have "maintaining dirt roads costs twice as much as paved roads costs." And that has a subject-verb problem, and also isn't a correct comparison: we would need to compare "maintaining dirt roads" with "maintaining paved roads", and not with "paved roads costs."

This logic is similar to what you'll see in my explanations for answer choices (B) and (C) above: https://gmatclub.com/forum/qotd-dirt-ro ... l#p1954811

I hope this helps!

(C) maintaining dirt roads costs twice as much as paved roads do

In maintaining dirt roads costs, dirt roads is not the subject of costs. Maintaining dirt roads is.

... maintaining dirt roads costs... ← "Maintaining something costs..."

AjiteshArun
So, subject-verb agreement is OK in the highlighted part, right?

This is all about being supremely literal with comparisons, as we'll discuss in this week’s YouTube webinar. And I don't think that anybody really loves comparisons, so… I dunno, try to enjoy this one anyway.


This is literally saying that dirt roads themselves cost more than maintaining paved roads. That doesn’t work: we either need to compare “maintaining dirt roads” to “maintaining paved roads” or we can compare the two types of roads. But (A) makes no sense in its current form.


This sounds pretty good! The key here is that the word “do” can replace a verb phrase – and in this case, “do” replaces “cost… to maintain.” So this is saying that “dirt roads cost twice as much to maintain as paved roads [cost to maintain].” Great, that makes sense. Let’s keep (B).
Here, "do" can also refer to "cost" and not "cost to maintain", right? And, in case it refers only to "cost", the sentence is no longer logically parallel as:
"dirt roads cost twice as much to maintain as paved roads COST". This could mean:
i). dirt roads cost twice to maintain VS the cost of main roads - illogical comparison, right?
ii). dirt roads cost twice to maintain VS paved roads cost [to maintain] - Here, can we consider that "to maintain" is omitted? If yes, how do we decide if it's omitted?
How do we conclude that it refers to "cost to maintain", and not just to "cost".



This is lamentably subtle. Keep in mind that “do” replaces a verb phrase – and “maintaining” is a noun (gerund) in this case, and definitely not a verb. (For more on –ing words, check out this article: https://gmatclub.com/forum/experts-topi ... 39780.html.) So this is literally saying that “maintaining dirt roads costs twice as much as paved roads [cost].” Now we’re comparing the cost of maintaining dirt roads with the cost of paved roads themselves, and that doesn’t makes sense.

Tricky, but definitely wrong. (C) is gone.


The “it” jumps out at me here. If we’re being charitable, I suppose we could accept the idea that “it” refers back to “maintaining”, since “maintaining” is a noun. So we have “maintaining dirt roads costs twice as much as [maintaining] does for paved roads.” Really? I guess that’s not totally illogical, but it’s a muddy mess, and it’s a whole lot less clear than (B). So (D) is out, since (B) is undoubtedly clearer.


I don’t see any reason why we would use the infinitive “to maintain” as a noun here. That’s not something that you’ll see very often in correct answers on the GMAT. I’m not 100% certain that it’s absolutely wrong, but it’s definitely inferior to (B).

Just as importantly, if we’re going to use the infinitive “to maintain” as the subject of the clause, then it’s only going to makes sense if the comparison is parallel. Something like “to maintain dirt roads costs twice as much as to maintain paved roads” would at least be parallel. (E) in its current form doesn’t make any sense, since “to maintain dirt roads” is compared with just the prepositional phrase “for paved roads.”

So (B) is our winner.