Most efforts to combat such mosquito-borne diseases like malaria and dengue have focused either on the vaccination of humans or on exterminating mosquitoes with pesticides.


(A) like malaria and dengue have focused either on the vaccination of humans or on exterminating

(B) like malaria and dengue have focused either on vaccinating of humans or on the extermination of

(C) as malaria and dengue have focused on either vaccinating humans or on exterminating

(D) as malaria and dengue have focused on either vaccinating of humans or on extermination of

(E) as malaria and dengue have focused on either vaccinating humans or exterminating

Correct: Proper idiomatic phrase is used "such . . .as", and "vaccinating" and "exterminating" are parallel

As an addendum to my earlier posting, let may say that all the five choices in the context are active voice sentences; so the use of active versus passive voice is not tested here. In addition, Choice C, D and E use the template: such as x and y and not such x as y
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Merely saying vaccinating may mislead. Used as an adjectival phrase, vaccinating humans may refer to those humans who do the job of vaccination. Vaccinating is a present participle and not a gerund in that instance. However, vaccinating of humans is out and out a gerund. That is why for use as a gerund, we may add the preposition of to be sure

Parallelism error is one of the most used aspects of sentence structure at least in GMAT. Although purely singular errors such as lack of parallelism alone may appear rarely in GMAT, the normal practice often is to cobble two or three errors together, of which parallelism will be one either as the primary error or as a secondary error.
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I am vaccinating is not used in the sense of gerund which i a noun. Because of the addition of am to the present participle vaccinating, I am vaccinating turns into a present progressive, which is a verb.

If you have any further doubts, you may perhaps like to read some good guide on the verbals namely present and past participles, gerunds and infinitives – may be MGMAT’S SC guide.
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In GMAT English "such as" is to be used always to present a list, not "like".
Hence (A) and (B) incorrect.

Secondly -Correct usage of Either "X" or "Y" - X and Y should be in same form

C and D put incorrect "on" before exterminating.

Hence
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Hey folks!
I have a simple question on which I, as a non-native speaker, am having some difficulties.
We all know that according to parallelism, all parallel clauses should begin with the same preposition or relative clause, but I have seen so many confusing structures, I had to ask this question:

Consider the following sentence:
I lost my final paper, to which I have spent great effort and a great sum of money. (Disregard the meaning since I couldn't come up with a scenario )

As the meaning is clear here we opted to not repeat "to which". But when should one repeat the clause or the preposition?
I was also going the ask the 138th SC from OG13, but I figured it out, so I'll be glad if you could reaffirm me:

Most efforts to combat such mosquito-borne diseases like malaria and dengue have focused either on the vaccination of humans or on exterminating mosquitoes with pesticides.

A and dengue have focused either on the vaccination of humans or on exterminating
B like malaria and dengue have focused either on vaccinating of humans or on the extermination of
C as malaria and dengue have focused on either vaccinating humans or on exterminating
D as malaria and dengue have focused on either vaccinating of humans or on extermination of
E as malaria and dengue have focused on either vaccinating humans or exterminating

Since the paralellism should be between two clauses of either.... and or.... the OA is E. But what if C was something like "as malaria and dengue have focused on either vaccinating humans or exterminating" (without the 2nd "on")
Would that be also true?

I know I could have been clearer with the question I asked, but I think the experts here will understand what I mean.
I gladly await your response in my final day before the GMAT :D

Thanks in advance,
Cinar

Hi

I just did this question but did not focus on the "such...as" idiom. Instead, I tried to figure out whether we should use "like" vs "as".
In my notebook I wrote down, that "like" can only compare nouns, pronouns and noun phrases, whereas "as" can only compare clauses.

Here, the comparison is b/w "malaria" and "dengue" (both are nouns), so I went with A or B.

Can someone please clarify/help with understanding?

Thanks and best regards

Is such x as y even a separate idiom? I thought it meant the same as such as x and y.

Most efforts to combat such mosquito-borne diseases like malaria and dengue have focused either on the
vaccination of humans or on exterminating mosquitoes with pesticides.

A. like malaria and dengue have focused either on the vaccination of humans or on exterminating
Usage of “like” to present examples is incorrect

B. like malaria and dengue have focused either on vaccinating of humans or on the extermination of
Same error as in option A

C. as malaria and dengue have focused on either vaccinating humans or on exterminating
Parallelism Error : “on either VH or ET” is correct …since “on” is outside the “either..or” structure

D. as malaria and dengue have focused on either vaccinating of humans or on extermination of
Parallelism Error : “on either VH or ET” is correct …since “on” is outside the “either..or” structure

E. as malaria and dengue have focused on either vaccinating humans or exterminating
Correct
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