Recently physicians have determined that stomach ulcers are not caused

The problem is that "are by" doesn't mean anything here. Notice that we already have the verb "are," so one way to read B would be "are not (caused by X) but are are by y." Another way to think about it is that "caused" isn't really a verb here--it's a past participle. It describes where stomach ulcers come from, not what they do. Making it parallel to a simple verb ("are") doesn't work.

If we don't want to put "caused" before the first parallel marker ("not"), as in C, then we need it after each marker: NOT caused by x BUT caused by y. However, in this case there's no reason to use that longer form. C solves the problem much more elegantly.

My ultimate query is to fix B like your highlighted part. Now, it make sense to me. Many many thanks DmitryFarber!

Also, one more query:
Can I add choice F as possible correct choice?
Thanks__

Possible Choice F:
F) Recently physicians have determined that stomach ulcers are caused not by stress, alcohol, and rich foods, but by a bacterium that dwells in the mucous lining of the stomach

Normally, we don't use "and" with lists of negatives, because it's then unclear whether we mean to negate each of the items, or just all of them together as a group. In other words, if I say "I don't have a car and a bicycle," now you don't know whether I have just one of those things or neither of them. If I say "Ulcers are not caused by X, Y, and Z," I seem to be saying that the combination of XYZ does not cause ulcers, whereas I think the intent here is to say that none of those things cause ulcers at all.

Hi Experts,

Are there any differences in sentence meaning between "ulcers are not caused by X but by Y" and "ulcers are caused not by X but by Y"?

TIA!

lybeaver The first version doesn't work. If we use the form "not . . . but," it creates a parallel structure. Whatever follows "not" has to match what follows "but." As long as we make our terms parallel, we can contrast as much or as little of a phrase as we want. Consider the following three options, all of which work grammatically, at least in theory:

Ulcers are NOT caused by x BUT caused by y.
Ulcers are caused NOT by x BUT by y. (This form probably strikes the best balance for this particular statement.)
Ulcers are caused by NOT x BUT y. (This doesn't work well, but keep reading.)

Most folks would find the first overly wordy, but it's not wrong, and this kind of form is quite common if the two verbs are different. For instance, we might say "Most great poems are NOT created in a flash inspiration BUT RATHER crafted painstakingly through many hours of revision."

The last form (with just x and y as parallel terms) would probably not fly on the GMAT, simply because "by not x" sounds confusing. It almost seems like we're saying that "not x" caused something. Why do that when we can fix the problem by putting "by" after "not"? However, look at this usage: "I was visited by not one but three members of the team." This makes sense, since "not one but three" is basically just a way to emphasize that three is a large number in this context. While it wouldn't be wrong to say "I was visited not by one but by three members of the team," but it doesn't create the same emphasis.

So, long story short? Start by making sure that whenever we have closed markers (not only/but also, either/or, etc.), the words/phrases after each marker match precisely. Typically, we want the exact same part of speech, although we might have, for instance, a noun in one case and a modified noun in the other. ("I want not only a cookie but also a warm blanket.") Don't automatically cut a choice for repeating too much (e.g. "not caused by X but caused by Y") unless the repetition creates an error. Then, look to make sure that the complete structure works to convey the intended meaning.

Recently physicians have determined that stomach ulcers are not caused by stress, alcohol, or rich foods, but a bacterium that dwells in the mucous lining of the stomach.


(A) not caused by stress, alcohol, or rich foods, but

(B) not caused by stress, alcohol, or rich foods, but are by

(C) caused not by stress, alcohol, or rich foods, but by

(D) caused not by stress, alcohol, and rich foods, but

(E) caused not by stress, alcohol, and rich foods, but are by


NOT BY "X" BUT BY "Y" IS THE CORRECT PHRASE. SO C IS THE ANSWER

+1 for C

caused not by stress, alcohol, or rich foods, but by- maintains parallelism (not by....but by)

GMATNinja egmat

(C) caused not by stress, alcohol, or rich foods, but by
(E) caused not by stress, alcohol, and rich foods, but are by

Let's add one more option to this question.
If we remove "are" from option E and the option (F) becomes
(F) caused not by stress, alcohol, and rich foods, but by

Then, we do not get the idea from the non-underlined sentence that whether it is asking for one of the causes among stress, alcohol, and rich foods or all three.

Will option (F) be right or wrong? Please advice.

Thanks

Points to ponder : This is a example where u can be really mechanistic about the parallelism and that's good.
So we can see a 3-2 split between 'not caused by'...and 'caused not by..'
If we want to use 'not caused by'.. construction it should be as following : not caused by x but caused by Y to maintain the parallelism.
However if we use the second structure ,t should be as following : caused not by X but by Y
With that in mind lets check the options

(A) not caused by stress, alcohol, or rich foods, but


(B) not caused by stress, alcohol, or rich foods, but are by


(C) caused not by stress, alcohol, or rich foods, but by

(D) caused not by stress, alcohol, and rich foods, but

(E) caused not by stress, alcohol, and rich foods, but are by

C is the answer

Recently physicians have determined that stomach ulcers are not caused by stress, alcohol, or rich foods,but a bacterium that dwells in the mucous lining of the stomach.

Concepts tested - IDIOM, PARALLELISM

Not x but y is the correct idiom form where x and y should be parallel.

Recently physicians have determined that stomach ulcers are not caused by stress, alcohol, or rich foods,but a bacterium that dwells in the mucous lining of the stomach.

(A) not caused by stress, alcohol, or rich foods, but --- caused by AND a bacterium are not parallel
(B) not caused by stress, alcohol, or rich foods, but are by --- are not, so are appears before not and is common. Shouldn't be repeated after but. It becomes the form - are not caused by x... but are by
(C) caused not by stress, alcohol, or rich foods, but by --- correct, are caused is taken common, not by x but by y is clear, succinct and parallel
(D) caused not by stress, alcohol, and rich foods, but --- same as a - by is missing after but
(E) caused not by stress, alcohol, and rich foods, but are by --- same as b, are caused not by... but are

[quote="freetheking"]Recently physicians have determined that stomach ulcers are not caused by stress, alcohol, or rich foods, but a bacterium that dwells in the mucous lining of the stomach.


(A) not caused by stress, alcohol, or rich foods, but

(B) not caused by stress, alcohol, or rich foods, but are by

(C) caused not by stress, alcohol, or rich foods, but by

(D) caused not by stress, alcohol, and rich foods, but

(E) caused not by stress, alcohol, and rich foods, but are by

This is a straightforward Parallelism-based question. Parallelism covers a number of aspects such as tenses, gerunds, comparisons and correlative conjunctions.

This question tests the concept of parallelism of correlative conjunctions. Correlative conjunctions are joining words that are used in pairs. The pairing is idiomatic or fixed in usage.

There are two aspects of parallelism of correlative conjunctions:
• The idiomatic pair must be used; the conjunctions cannot be mixed up. For example, either cannot be followed by nor. The various pairs of correlative conjunctions are either-or, neither-nor, not only-but also, from-to, between-and, both-and not-but.
E.g.: We can play both tennis as well as badminton here. (incorrect)
We can play both tennis and badminton here. (correct)

• The two conjunctions must be followed by the same part of speech. For example, if ‘either’ is followed by a verb, ‘or’ must also be followed by a verb in the sentence.
E.g.: I neither want chocolate nor ice cream. (incorrect because ‘neither’ is followed by the verb ‘want’ but ‘nor’ is followed by the noun ‘ice cream’.)

I want neither chocolate nor ice cream. (correct because both the conjunctions are followed by nouns.)

In the given question, the correlative conjunctions ‘not-but’ have been used. The sentence contains a verb in the passive form – are caused. The helping/auxiliary verb ‘are’ is in the non-underlined portion of the sentence. But the participle ‘caused’ is in the underlined portion of the sentence. The helping verb and participle should be together in order to maintain parallelism in the sentence.

Let us analyze the options according to rule 2 of parallelism of correlative conjunctions –
(A) not caused by stress, alcohol, or rich foods, but
- Incorrect because the conjunction ‘not’ is followed by the verb(participle) ‘caused’ and the conjunction ‘but’ is followed by a noun ‘a bacterium’ (in the non-underlined part of the sentence)

(B) not caused by stress, alcohol, or rich foods, but are by
- Incorrect because the conjunction ‘not’ is followed by the verb (participle) ‘caused’ and the conjunction ‘but’ is followed by the helping/auxiliary verb ‘are’. The helping verb is already present in the non-underlined part of the sentence. If a verb is to be repeated, the participle form ‘caused’ is to be repeated.

(C) caused not by stress, alcohol, or rich foods, but by
- Correct because the participle ‘caused’ has been shifted next to the helping/auxiliary verb ‘are’ and the conjunctions ‘not’ and ‘but’ are bith followed by the preposition ‘by’.

(D) caused not by stress, alcohol, and rich foods, but
- Incorrect because the conjunction ‘not’ is followed by the preposition ‘by’ and the conjunction ‘but’ is followed by the noun ‘a bacterium’(in the non-underlined part of the sentence).

(E) caused not by stress, alcohol, and rich foods, but are by
- Incorrect because the conjunction ‘not’ is followed by the preposition ‘by’ and the conjunction ‘but’ is followed by the helping verb ‘are’.

Therefore, C is the most appropriate option.
Jayanthi Kumar.

Recently physicians have determined
that stomach ulcers are not caused by stress, alcohol, or rich foods,
but a bacterium that dwells in the mucous lining of the stomach.


(A) not caused by stress, alcohol, or rich foods, but

(B) not caused by stress, alcohol, or rich foods, but are by

(C) caused not by stress, alcohol, or rich foods, but by

(D) caused not by stress, alcohol, and rich foods, but

(E) caused not by stress, alcohol, and rich foods, but are by


IMO C
[/quote]

Hello experts!

Is there a notable meaning difference between "not caused by" and "caused not by"? Moreover, is it always the case that you need to follow up the helping verb IMMEDIATELY with another verb? (e.g., "are CAUSED...") Or can you have "not" or another word in between?

The two phrases create different expectations for what's likely to follow. If I see "not caused by," all I know is that afterwards I'm getting the noun that is not responsible for something. For example:

After much deliberation, Tim's doctor determined that the rash was not caused by the 17 bags of Skittles Tim consumed.

Here, we get one element that is not responsible for Tim's rash: the 17 bags of Skittles. Simple enough.

However, "caused not by" signals to the reader that we're going to get two pieces next: the element that is not responsible, as well as whatever is responsible:

After much deliberation, Tim's doctor determined that the rash was caused not by the 17 bags of Skittles Tim consumed but by the toilet bowl cleaner he'd rubbed all over his face and chest.

So now we have two pieces of information: what didn't cause Tim's rash, as well as the real culprit.

As for "immediately," there's no rule. It's an adverb, so it's telling us when an action occurs, but it doesn't have to come right before the verb it modifies. I could write, "Tim immediately experienced itchiness and watery eyes," but I could also write "Immediately, Tim experienced itchiness and watery eyes." Either is fine.

I hope that helps!

Is it okay to write

" not caused by stress, alcohol, or rich foods, but by "

I think that the missing "caused" after "but" should be an error

Correct Answer : C

Correct idiom : Casued not by X, But by Y
Parallelsim : We need check after parallelism indicators like (,and)(,or) etc the structure must be same

Recently physicians have determined that stomach ulcers are not caused by stress, alcohol, or rich foods, but a bacterium that dwells in the mucous lining of the stomach.
(A) not caused by stress, alcohol, or rich foods, but
(B) not caused by stress, alcohol, or rich foods, but are by
(C) caused not by stress, alcohol, or rich foods, but by
(D) caused not by stress, alcohol, and rich foods, but
(E) caused not by stress, alcohol, and rich foods, but are by