When working with liquids in a chemicals laboratory, it is advisable

Question

When working with liquids in a chemicals laboratory, it is advisable  not only to always add acid to water but also to do it by stirring slowly, as it  prevents dangerous overheating.

A. not only to always add acid to water but also to do it by stirring slowly, as it

B. to always add acid to water but also to do it by stirring slowly, as it

C. not only to always add acid to water but to do so by stirring slowly, as doing so

D. not only to always add acid to water but also to do so by stirring slowly, as doing so

E. not only to always add acid to water but also to do so by stirring slowly, as it

Bunuel · Accepted Answer

OFFICIAL EXPLANATION

When working with liquids in a chemicals laboratory, it is advisable  not only to always add acid to water but also to do it by stirring slowly, as it  prevents dangerous overheating.

A. not only to always add acid to water but also to do it by stirring slowly, as it

This answer choice is grammatically incorrect. In the GMAT, not only must be complemented by but also.

What helps us identify this question as a Parallelism question as well as identify the mistake is the following Stop Sign:

not only... but also...

What helps us identify this question as a Pronoun question is the following Stop Sign:

Any pronoun in the underlined part or after it.

B. to always add acid to water but also to do it by stirring slowly, as it

This answer choice is grammatically incorrect for two reasons:

1. A pronoun (in this case,  it ) should to a previously mentioned noun. In this answer choice, the pronoun(s) incorrectly refer to a verb ( to add acid  for the first 'it';  stirring slowly  for the second). If we wish to refer to a previously mentioned verb, we need to use the phrase  to do so  or  doing so .

What helps us identify this question as a Pronoun question is the following Stop Sign:

Any pronoun in the underlined part or after it.

2. In the GMAT,  but also  must be complemented by  not only .

What helps us identify this question as a Parallelism question as well as identify the mistake is the following Stop Sign:

not only... but also...

C. not only to always add acid to water but to do so by stirring slowly, as doing so

This answer choice is grammatically incorrect. In the GMAT,  not only  must be complemented by  but also .

What helps us identify this question as a Parallelism question as well as identify the mistake is the following Stop Sign:

not only... but also...

D. not only to always add acid to water but also to do so by stirring slowly, as doing so

Absolutely right!

This answer choice corrects the original Pronoun mistake by replacing the incorrectly used pronoun  it (also to do it...as it)  with the correct phrases to do so and doing so ( also to do so....as doing so ).

Remember that a pronoun (in this case,  it ) should refer to a previously mentioned noun. If we wish to refer to a previously mentioned verb, we need to use the phrase  to do so  or  doing so . The original sentence contains two errors in which the pronoun  it  refers to a verb ( to add acid  for the first 'it';  stirring slowly  for the second).

E. not only to always add acid to water but also to do so by stirring slowly, as it

This answer choice is grammatically incorrect. A pronoun (in this case, it) should refer to a previously mentioned noun. In this answer choice, the pronoun(s) incorrectly refer to a verb (to add acid for the first 'it'; stirring slowly for the second). If we wish to refer to a previously mentioned verb, we need to use the phrase to do so or doing so.

What helps us identify this question as a Pronoun question is the following Stop Sign:

Any pronoun in the underlined part or after it.

What helps us identify this question as a Pronoun question is the following Stop Sign:

Any pronoun in the underlined part or after it.

zhanbo · Answer

While I feel that all opinions are problematic, I ended up choosing (E).

Who is "working with liquids in a chemicals laboratory"? The subject of the sentence ("it") cannot be the agent who is working in a lab. All five opinions are thus incorrect.

After ignoring the glaring mistake, we can eliminate (AB) because "it" in "do it" does not have clear antecedent. "do so" is needed. In at least 90% of GMAT questions that contain "do it" and "do so" split, "do so" is preferred.

Eliminate (C) because it does not use "but also" to be parallel with "not only".

Now, we have to pick the winner from D and E. Their only differences are "as doing so" VS. "as it". 
In (D), there are two "doing so" in quick succession, and their meanings are different. The first ”doing so" means "adding acid to water", and the second “doing so" refers to "stirring slowly while adding acid to water". It is not only awkward but also jarring to reuse the same "doing so" while switching its meanings. A clear sentence should not ask readers to decipher what each "doing so“ stands for. 
In (E), it can refer to ”stirring slowly". (Some argue that, in GMAT, it cannot refer to gerund. I have been ambivalent about this idea).

So I choose (E) over (D).

Sumi1010 · Answer

When working with liquids in a chemicals laboratory, IT is advisable  not only   to always add acid to water   but also   to do IT by stirring slowly , as IT prevents dangerous overheating.

The construction : Not Only ... but also ... - is correct in this sentence. 
Let's look at the pronoun IT.

1st IT is a placeholder and does not stand for a noun. Hence,correct.
Placeholder IT follows with infinitive (To ...) or noun-clause (That....)
Examples - 
  It is good TO laugh.
It is good that I remain calm while solving GMAT problems .

2nd IT - is incorrect, 
To do IT - we need a specific noun in this case.But IT here wants to stand for "add acid to water" i.e. incorrect.
To do SO - is the correct construction for referring back an action.

3rd IT - is incorrect again.
Ask yourself - What prevents dangerous overheating? 
There is not a noun subject.
It is the action of adding acid to water by stirring slowly.
We again need SO to refer back the action.

Let's look at the choices -

A. not only to always add acid to water but also to do  it  by stirring slowly, as it
 Incorrect IT 
B. to always add acid to water but also to do  it  by stirring slowly, as it
 Incorrect IT 
C. not only to always add acid to water  but to  do so by stirring slowly, as doing so
 But "also" is required if we add more information. "But" without "also" implies a contrast. 
D. not only to always add acid to water but also to do so by stirring slowly, as doing so
 Correct. 
E. not only to always add acid to water but also to do so by stirring slowly, as  it 
 Incorrect IT

IMO  D

jatin093 · Answer

When working with liquids in a chemicals laboratory, it is advisable not only to always add acid to water but also to do it by stirring slowly, as it prevents dangerous overheating.

A. not only to always add acid to water but also to do it by stirring slowly, as it --> incorrect usage of 'it'

B. to always add acid to water but also to do it by stirring slowly, as it --> incorrect idiom usage

C. not only to always add acid to water but to do so by stirring slowly, as doing so --> incorrect idiom usage

D. not only to always add acid to water but also to do so by stirring slowly, as doing so --> Correct (by removing 'it')

E. not only to always add acid to water but also to do so by stirring slowly, as it --> incorrect usage of 'it'

100mitra · Answer

Correct Option D

When working with liquids in a chemicals laboratory, it is advisable  not only to always add acid to water but also to do it by stirring slowly, as it  prevents dangerous overheating.

Sentence Exam on: 
- Idiom Not only X but also Y

Eliminate B, and C - Idiom Error 
B. to always add acid to water but also to do it by stirring slowly, as it
C. not only to always add acid to water but to do so by stirring slowly, as doing so

Eliminate A, and E - Pronoun singular "It" creates ambiguity and compared with verb 
A.  not only to  always add acid to water  but also to  do    it    by stirring slowly,    as it   
E.  not only to  always add acid to water  but also to  do so by stirring slowly,    as it

Correct Option D 
D.  not only to  always add acid to water  but also to     do so     by stirring slowly, as d   doing so

sivatx2 · Answer

A. not only to always add acid to water but also to do  it  by stirring slowly, as  it  
 Pronoun reference error with multiple usage of it. It refers to what - add acid, 'stirring', laboratory. Eliminate

B. to always add acid to water  but also  to do it by stirring slowly, as  it  
 not only....but also is the correct idiom. Here "not only" is missing. Eliminate

C.  not only  to always add acid to water  but  to do so by stirring slowly, as doing so 
 not only....but also is the correct idiom. Here 'also' is missing. Eliminate

D. not only to always add acid to water but also to do so by  stirring  slowly, as  doing  so 
 'as doing so' is maintaining the parallel with 'stirring'. keep

E. not only to always add acid to water but also to do so by stirring slowly, as  it  
 Pronoun reference error with multiple usage of it. It refers to what - add acid, 'stirring', laboratory. Eliminate

So D is the best answer choice.

When working with liquids in a chemicals laboratory, it is advisable

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GMAT Sentence Correction (SC - EA only) Questions

When working with liquids in a chemicals laboratory, it is advisable

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