By pressing a tiny amount of nitrogen between two diamonds

[kris]

By pressing a tiny amount of nitrogen between two diamonds to a pressure of 25 milliion pounds per square inch, scientists not only were able to transform the gas into a solid, but they also created a semiconductor similar to silicon

A.
B. not only were able to transform the gas into a solid but also creating
C. were able not only to transform the gas into a solid but to create
D. were able not only to transform the gas into a solid but also creating
E. were able not only to transform the gas into a solid but they were also able to create

I am surprised by the answer. Is it acceptable to omit " also" in "not only x , but also y" structure.

[RonPurewal]

yes, it is.
[editor: see the long post below for a much more complete treatment of this idiom.]

keep in mind for future questions that it IS acceptable to phrase the expression that way!

[Kris]

Ron Purewal,

Thanks for clarification

[Guest]

what was the OA ?

[RonPurewal]

the oa is (c), the only choice that exhibits proper parallel structure.

[Guest]

I agree with C, but with E is it only because it is very verbose - it seems parallel, and respect the not only - but also..

[StaceyKoprince]

E isn't parallel.

Parallel would be "were able // not only (to X) but also (to Y)" ("were able" applies to both parts, while "to X" and "to Y" are parallel)

But this choice says "were able // not only (to X) but they were also (able to Y)"

So the opening "were able" should apply to both sets of parentheses, which would give us "were able able to Y." Which is obviously not grammatically correct. :)

[tathagat]

Hi,
Whats wrong with the parallelism in A?
It appears to be correct? (Is the insertion of they in "but they also" a problem??)

Thanks,

[RonPurewal]

Hi,
Whats wrong with the parallelism in A?
It appears to be correct? (Is the insertion of they in "but they also" a problem??)

Thanks,

if it appears to be correct, you're thinking too much.

if you have a two-part parallel construction - such as "not only ... but also" - your detection of parallelism (or lack thereof) should be COMPLETELY mechanical. just look at the words that follow the first part, and look at the words that follow the second part (and DON'T ignore any words). if they don't have the same grammatical structure, then the parallelism is faulty. end of story.

choice (a):
not only were able to transform the gas into a solid, but they also created
the blue parts aren't parallel, because there's a subject in the second part but not in the first. and you are not, not, NOT allowed to ignore "they" in the second part.
and because "scientists" comes before "not only", you must ignore it.

[vscid]

E isn't parallel.

Parallel would be "were able // not only (to X) but also (to Y)" ("were able" applies to both parts, while "to X" and "to Y" are parallel)

But this choice says "were able // not only (to X) but they were also (able to Y)"

So the opening "were able" should apply to both sets of parentheses, which would give us "were able able to Y." Which is obviously not grammatically correct. :)

So here, parallelism takes preference over idiomatic construction.
How does one decide at the last minute, which to prefer when ?

[RonPurewal]

So here, parallelism takes preference over idiomatic construction.

not really. what's actually happening is that there's a second correct idiom, "not only ... but ...", which you just didn't happen to know.
[editor: see the long post below for a much more complete treatment of this idiom.]

remember that idiomatic construction is entirely up to the preferences of the gmat staff; there will always be one or two constructions that you just didn't know. occasionally, the gmat even surprises or frustrates me with its choices of correct and incorrect idioms, and i've seen lots and lots and lots of formal written english.

How does one decide at the last minute, which to prefer when

not even a question. parallel structure always takes precedence. it's entirely black and white, right or wrong, and is the single most commonly tested grammatical issue on the test.
idiomatic construction is full of surprises (like the one in this post!), and is anything but clear-cut. it should be last priority, after all actual grammatical issues, unless you are ABSOLUTELY SURE that you are correct about it.

[RonPurewal]

actually, here's a more accurate take on what's going on here.

IN ACTUALITY, there is really only one base structure here, which is "not ... but ..."

that's actually the only TRUE set of parallel markers here. "only" and "also" are adverbs, and so ultimately function as modifiers -- i.e., they aren't necessary to the structure.
still, since "not only ... but also ..." is so common, you may want to memorize it separately -- but be aware that this is NOT the only correct form of this idiom.

the MOST reliable way to deconstruct this idiom is just to memorize "not ... but ...", and then ignore the adjectives "only" and "also" in deciding whether structures are grammatically parallel.
in deciding the MEANING of the structure, you can't dismiss "only" and "also" ... but that's a separate issue. see below.

--

EXAMPLES:
BE SURE YOU CAN UNDERSTAND WHY EACH OF THESE IS CORRECT OR INCORRECT

the writer was not only mortified by her mistake but determined to correct it in print.
--> CORRECT

the writer not only was mortified by her mistake but was determined to correct it in print.
--> CORRECT

the writer was not only mortified by her mistake but was determined to correct it in print.
--> INCORRECT

the small child was relieved to hear that the rustling under the bed was caused not by a ghost but by his pet cat.
--> CORRECT

the small child was relieved to hear that the rustling under the bed was caused not by a ghost but his pet cat.
--> INCORRECT

--

SO WHAT'S THE DIFFERENCE, THEN, WITH
"not only ... but also ..."
"not only ... but ..."
"not ... but ..."
?

the difference here is strictly one of MEANING.

the first two are pretty similar; the last one is TOTALLY different.

(1) "not only ... but also ..." is used to refer to two descriptions that REINFORCE each other (i.e., both have the same connotation -- two good things, two bad things, two helpful things, etc.), but are fundamentally independent.
ex:
this drug is not only an alertness aid, but also an antidepressant.
--> "alertness aid" and "antidepressant" are TWO GOOD THINGS that have basically NOTHING TO DO WITH EACH OTHER.
therefore, "not only ... but also".

(2) "not only ... but ..." is also used to refer to two descriptions that REINFORCE each other, but it's generally used when the second description EXPANDS or GOES BEYOND the first.
ex:
ryan not only competed in all the events, but won first prize in three of them.
--> note that "won first prize in three of [the events]" is an EXTENSION of "compet[ing] in all the events". these are not independent.

the above difference between (1) and (2) is subtle, and is therefore not terribly important. however, you MUST be able to tell those from the next one:

(3) "not ... but ..." is used when the FIRST thing is EXPECTED, ASSUMED, or PREVIOUSLY THOUGHT, but is REFUTED / CONTRADICTED / DISPROVED by the SECOND thing.
ex:
the snacks known as "french fries" were invented not in france, but in belgium.
--> the initial assumption, which is refuted, is that french fries are from france.

[aimingformba]

Ron, great explanation. Thanks.

[zarak_khan]

Fantastic explanation!! Thanks, Ron.

[StaceyKoprince]

yw!