zoezhuyan
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
(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!
(3c) "... 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.
after reading this thread, I got an idea that both 2c and 3c are correct.
Dear
zoezhuyan,
I'm happy to respond.

Yes, (2c) and (3c) are correct. This construction is subtle and sophisticated: I certainly can understand why it would be puzzling to someone who has learned English as a second language!
Of course, part of what is hard is that common words have been omitted in the second branch of the parallelism and we have figure out what those are. See:
Dropping Common Words in Parallel on the GMATLet's look at these with the extra words put back in.
The version in (B)
(B expanded) ...
the cost of running nuclear plants is about the same as the cost is for other types of power plants...
This is 100% correct. Why is "
for" used in this construction? It sounds so right to a native ear, but it's hard to put this in words. Sometimes, the preposition "
for" is used for a separate situation or case, for the experience of another person or the process of another object.
I love opera, but the experience is not the same for her.
Americans stridently clamor for individual liberties, but for the Chinese, responsibilities to the family and to the country are more meaningful.
The lion struts across the Serengeti as if it owns the place, but for the gazelle, this large plain is forever a precarious place of danger.
We can reheat leftovers, but for frying food, we need a stove top.
Once again, this is a sophisticated structure, used only in very high quality writing.
This is the construction used in (B). This compares two nouns, "
cost" to "
cost." If we drop the implied extra words, we get:
(B) ...
the cost of running nuclear plants is about the same as for other types of power plants ....
That's the OA.
The version in (C) & (D), instead of the noun "
cost" we use the verb "
it cost." Here are the words in (C) and in (D)
(CD) ...
it costs about the same to run nuclear plants as for other types of power plants...
This involves the
empty "it" construction: the subject of the verb "
costs" is the infinitive "
to run" after the verb. I would say that I unfairly criticized this construction in one of the posts above. This is fine. The expanded version is:
...
it costs about the same to run nuclear plants as it costs for other types of power plants ...
That part of (C) & (D) is correct, but those two have other problems!
In (C), both clauses begin with "
it" but it's not the same "
it." Typically, when the same pronoun opens the two clauses of a sentence, this pronoun has the same reference. This is not the case at all in (C), and that mismatch creates a very awkward sentence.
In (D), I would say everything up to the first comma is fine, but the "
they" is ambiguous, and "
stemming from" is an extremely awkward construction.
Does all this make sense now, my friend?
Have a wonderful weekend.
Mike