mikemcgarry wrote:
I'm happy to respond.

I see that my intelligent colleague
sayantanc2k already gave you a good response. I just want to add a little more.
Think about what parallelism is. Many students mistakenly believe that parallelism is a grammatical structure. It's not. It's a logical structure, a logical matching pattern, and the grammar simply mirrors the logic. In fact, the grammar has only to match enough to make the logic clear. Sometimes, additional matching creates a strong rhetorical effect, but there is absolutely no requirement that parallelism should involve lockstep precision between the two branches down to the last detail.
cost of X and the cost of YThat's a very sensible pattern of matching: the parallel grammar makes clear the logic.
Now, suppose X is a noun and Y is a gerund phrase.
the cost of auto insurance and the cost of getting a speeding ticketThe real question is whether these are logically parallel? Are these two costs of the same category, the kind we would compare and contrast? Yes! A person in the real world might have make one payment for her auto insurance and another payment because she got a speeding ticket. These are logically similar, so the parallelism works. The fact that we have the matching "
cost of" pair is enough to indicate the pattern of matching: that's all the grammatical matching we need. It doesn't matter at all that the X & Y are different parts of speech.
By contrast, we could have the same parts of speech, two nouns, and the parallelism could be complete nonsense:
I made dinner with the leftovers in the refrigerator and with my friend Chris.
Either "
with" statement alone would be fine, but together they are a train wreck. The first "
with" suggest the materials and the second one suggest accompaniment. These are NOT logically parallel at all, even though the grammar is the same.
On the GMAT SC, you can't afford to pay attention only to the grammar. Grammar and logic and rhetoric are three equally important strands.
Does all this make sense?
Mike

thanks so much Mike
I am glad that I got your explanation, I like your courses on
magoosh.
you are right, I pay more attention to grammar parallelism. because I am not native speaker, to understand the sentence is a little harder for me.
for this case, I am sunk in the prep "
for",
but I am afraid I need your further explanation:
mikemcgarry wrote:
Let's start with your two sentences
(1a)
The cost of running nuclear plants is about the same as the cost of running other types of power plants. = wordy but OK
(1b)
The cost of running nuclear plants is about the same as that of running other types of power plants. = not much better
Because of the phrasing, it's not immediately obvious how to omit repeated words to shorten this more without introducing ambiguity or awkwardness. This is not a structure that lends itself to elegant revisions.
(2a)
It costs about the same to run nuclear plants as it costs to run other types of power plants. = correct but too wordy
(2b)
It costs about the same to run nuclear plants as to run other types of power plants. = better, with the common words "
to run" dropped in the second branch.
(2c)
It costs about the same to run nuclear plants as for other types of power plants. = even more elegant: this is what the GMAT loves!
Now, look at the structure in the OA:
(3a) "...
the cost of running nuclear plants is about the same as the cost of running other types of power plants ..." = that's the full version. That's grammatically correct but a rhetorical disaster! It reeks of redundancy! We need to drop some of the repeated words.
(3b) "...
the cost of running nuclear plants is about the same as that of running other types of power plants ..." = only slightly better
(3b) "...
the cost of running nuclear plants is about the same as for other types of power plants ..." = an elegant gem! Again, this is what the GMAT loves, and this is the version in the OA.
The very hard thing about this is that when we look at parallelism of a complex structure, it is up to us, the readers, to infer which repeated elements from the first branch have been omitted in the second branch. We get (2c) or (3c) printed on the page and we have to understand that everything in (2a) or (3a) is implicit in that.
Does all this make sense?
Mike

after reading this thread, I got an idea that both 2c and 3c are correct.
mikemcgarry wrote:
(B) While the cost of running nuclear plants is about the same as it is for other types of power plants
This is perfectly correct. A perfect comparison. This, of course, is the OA.
(C) Even though it costs about the same to run nuclear plants as for it costs to run other types of power plants
This one has the same structure, but because what comes before is different, the structure is problematic here. The preposition "for" is not needed here. A different set of words would be implied.
(D) It costs about the same to run nuclear plants as for it costs to run other types of power plants
Same problem as (C).
after reading this thread,
both option C and D are incorrect, because "for" is unnecessary.
I have no idea about difference between 2C,3C and C,D,
would you please clarify for me ?
another question :
as you said:
mikemcgarry wrote:
(B) While the cost of running nuclear plants is about the same as it is for other types of power plants
This is perfectly correct. A perfect comparison. This, of course, is the OA.
(C) Even though it costs about the same to run nuclear plants as for it costs to run other types of power plants
This one has the same structure, but because what comes before is different, the structure is problematic here. The preposition "for" is not needed here. A different set of words would be implied.
(D) It costs about the same to run nuclear plants as for it costs to run other types of power plants
Same problem as (C).
why not
(C) Even though it costs about the same to run nuclear plants as it costs to run
for other types of power plants(D) It costs about the same to run nuclear plants as it costs to run
forother types of power plantswaiting for your reply
have a nice day
>_~