Last visit was: 22 Apr 2026, 11:29 It is currently 22 Apr 2026, 11:29
Home
Messages
Tests
Schools
Events
Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
   1   2 
avatar
shoum27
avatar
Joined: 04 Dec 2016
Last visit: 11 Jun 2019
Posts: 22
Own Kudos:
38
Given Kudos: 37
Location: India
Schools: Insead Sept19 Intake (D) Georgia Tech '21 (D) Broad '21 (A) Kelley '21 (II) McCombs '21 (D) Fisher '21 (A$)
GMAT 1: 710 Q50 V35
GPA: 4
Schools: Insead Sept19 Intake (D) Georgia Tech '21 (D) Broad '21 (A) Kelley '21 (II) McCombs '21 (D) Fisher '21 (A$)
GMAT 1: 710 Q50 V35
Posts: 22
Kudos: 38
Industrialization and modern methods of insect control have improved 20 Apr 2017, 21:36
Kudos
Add Kudos
Bookmarks
Bookmark this Post
vishwaprakash
paeagain
Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.
A. while at the same time they have introduced some 100,000 dangerous chemical pollutants, having
B. while at the same time introducing some 100,000 dangerous chemical pollutants that have
C. while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have
D. but introducing some 100,000 dangerous chemical pollutants at the same time that have
E. but at the same time introducing some 100,000 dangerous chemical pollutants, having

POE

A. while at the same time they have introduced some 100,000 dangerous chemical pollutants, having
Incorrect - Ambiguous modifier ", Having" it has potential to modify pollutants and They (Industrialization and modern methods of insect control) Hence sentence is not clear to present an Idea.

B. while at the same time introducing some 100,000 dangerous chemical pollutants that have
Correct
1. introducing - Ving modifier modifies the subject of preceding clause ( Industrialization and modern methods of insect control)
2. That - correct modify Pollutants.


C. while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have
Incorrect -
1. Change of Meaning (Sin in GMAT SC) ,
Original Meaning - "At the same time, they have introduced 100,000 pollutants"
Meaning in option - "They have introduced 100,000 pollutant at the same time.

2. "Time, which" - which is modifying the time, Time modifier is when. Even tough Which modifies time, it introduced change in meaning by saying " Time gone viral .. "



D. but introducing some 100,000 dangerous chemical pollutants at the same time that have
Incorrect - Here But introduced an Independent clause and has no verb in it.
E. but at the same time introducing some 100,000 dangerous chemical pollutants, having
Incorrect - Here But introduced an Independent clause and has no verb in it.
Show more



Hi.
Pls elaborate on this...
C. while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have
Incorrect -
1. Change of Meaning (Sin in GMAT SC) ,
Original Meaning - "At the same time, they have introduced 100,000 pollutants"
Meaning in option - "They have introduced 100,000 pollutant at the same time.
User avatar
kavach
User avatar
Joined: 05 Mar 2017
Last visit: 06 Jul 2021
Posts: 177
Own Kudos:
177
Given Kudos: 687
Location: India
Concentration: General Management, Marketing
Schools: ISB '20 LBS '22 IE '22 Duke Fuqua SSE Int'l Business CEMS MiM "22 (S) ESSEC MiM "22 (S)
GPA: 3.6
WE:Marketing (Hospitality and Tourism)
Products:
My Reviews
Schools: ISB '20 LBS '22 IE '22 Duke Fuqua SSE Int'l Business CEMS MiM "22 (S) ESSEC MiM "22 (S)
Posts: 177
Kudos: 177
Industrialization and modern methods of insect control have improved 27 Dec 2018, 11:03
Kudos
Add Kudos
Bookmarks
Bookmark this Post
is the use of That CORRECT FOR Pollutants(Plural)
User avatar
KaranB1
User avatar
Joined: 17 Aug 2018
Last visit: 22 Oct 2025
Posts: 120
Own Kudos:
201
Given Kudos: 153
Location: India
Schools: IIMA WBS '22
GMAT 1: 640 Q46 V32
GMAT 2: 710 Q49 V38
Products:
My Reviews
Schools: IIMA WBS '22
GMAT 2: 710 Q49 V38
Posts: 120
Kudos: 201
Industrialization and modern methods of insect control have improved 01 Jan 2019, 15:48
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi GMATNinja @E-gmat

Please help me understand how A is incorrect grammatically.

I'm confused on the usage of "Having".
User avatar
CrackverbalGMAT
User avatar
Major Poster
Joined: 03 Oct 2013
Last visit: 22 Apr 2026
Posts: 4,846
Own Kudos:
9,180
Given Kudos: 226
Affiliations: CrackVerbal
Location: India
Expert
Expert reply
Posts: 4,846
Kudos: 9,180
Industrialization and modern methods of insect control have improved 15 Dec 2020, 00:23
Kudos
Add Kudos
Bookmarks
Bookmark this Post
paeagain
Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.


(A) while at the same time they have introduced some 100,000 dangerous chemical pollutants, having

(B) while at the same time introducing some 100,000 dangerous chemical pollutants that have

(C) while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have

(D) but introducing some 100,000 dangerous chemical pollutants at the same time that have

(E) but at the same time introducing some 100,000 dangerous chemical pollutants, having
Show more

This question is based on Construction.

The conjunction ‘while’ is used to convey the meaning of ‘at the same time as’. The conjunction ‘but’ conveys a contradiction.

The sentence conveys the idea that two things, albeit slightly contradictory, happened together. So, the conjunction ‘while’ is more appropriate than the conjunction ‘but’. Furthermore, the conjunction ‘but’ cannot be followed by a participle. There should be a verb after the conjunction. Since there is no verb after the conjunction in either of the options, D and E can be eliminated.

Option A has a participle modifier at the end. A participle modifier after a comma modifies the subject of the clause before it. So, the modifier modifies the pronoun ‘they’, which refers to “industrialization and modern methods of insect control” but it is not industrialization and methods of insect control that have gone unregulated. Since the meaning conveyed is illogical, Option A can be eliminated.

The modifier at the end of this option begins with the relative pronoun ‘which’. A relative pronoun refers to the noun placed immediately before it; in this sentence, the noun is ‘time’. Since it is not ‘time’ that has gone unregulated, the meaning conveyed by the placement of the modifier is illogical, and so, Option C can be eliminated.

Option B has the appropriate conjunction ‘while’, followed by the participle ‘introducing’; this option maintains the appropriate structure of the sentence to convey the idea that two actions – improving the standard of living and introducing dangerous pollutants – happened together. The modifier “that have gone unregulated…..” appropriately modifies “chemical pollutants”. Therefore, B is the most appropriate option.

Jayanthi Kumar.
User avatar
Gylmitul
User avatar
Joined: 03 Mar 2020
Last visit: 07 Apr 2021
Posts: 32
Own Kudos:
10
Given Kudos: 125
Location: India
Schools: ISB'22 (A)
GMAT 1: 710 Q49 V39
Schools: ISB'22 (A)
GMAT 1: 710 Q49 V39
Posts: 32
Kudos: 10
Industrialization and modern methods of insect control have improved 17 Dec 2020, 02:19
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi, Can someone please explain if parallelism is not necessary for two clauses/phrases joined by while?


daagh
kivalo wrote

Quote:
Can some explain to me the way 'introducing' is used in B. If it is a verb, how can it be parallel to 'have improved' ??? In case it is a present participle, how can it stand alongside 'while', which I understand is a subordinating conjuction that requires a full clause?

Apart from its usage as a conjunction with a finite verb, 'while' is also used along with participles. GMAT has accepted this usage also, as can be seen below. Therefore, one cannot omit a choice on this count.

1. The themes that Rita Dove explores in her poetry is universal, encompassing much of the human condition while occasionally she deals with racial issues.
A. is universal, encompassing much of the human condition while occasionally she deals
B. is universal, encompassing much of the human condition, also occasionally it deals
C. are universal, they encompass much of the human condition and occasionally deals
D. are universal, encompassing much of the human condition while occasionally dealing
E. are universal, they encompass much of the human condition, also occasionally are dealing

OA D

2. While studying the genetic makeup of corn, a new class of mutant genes was discovered by Barbara McClintock, a discovery which led to greater understanding of cell differentiation.

A. a new class of mutant genes was discovered by Barbara McClintock, a discovery which led
B. a new class of mutant genes in corn were discovered by Barbara McClintock, leading
C. Barbara McClintock discovered a new class of mutant genes, and it led
D. Barbara McClintock discovered a new class of mutant genes, a discovery that led
E. Barbara McClintock, who discovered a new class of mutant genes, leading

The non-underline part uses while along with a participle

3. Meteor showers and individual streaks of light that flash across the sky every night are generated when tiny flecks of celestial detritus, often no larger than grains of sand or of pebbles, burn up speeding through the atmosphere.

(A) grains of sand or of pebbles, burn up speeding
(B) grains of sand or pebbles, burn up while speeding
(C) grains of sand or pebbles, which burn up while speeding
(D) a grain of sand or pebble, which burns up as it speeds
(E) a grain of sand or a pebble burns up when it speeds

OA.B
Show more
User avatar
Ranasaymon
User avatar
Joined: 24 Nov 2019
Last visit: 22 Apr 2026
Posts: 320
Own Kudos:
274
Given Kudos: 838
Location: Bangladesh
GMAT 1: 600 Q46 V27
GMAT 2: 690 Q47 V37
GPA: 3.5
GMAT 2: 690 Q47 V37
Posts: 320
Kudos: 274
Industrialization and modern methods of insect control have improved 15 Mar 2021, 22:34
Kudos
Add Kudos
Bookmarks
Bookmark this Post
I can reach answer B by using POE. But one thing makes me confused. Are while and at the same time not redundant?
User avatar
CRACKGMATNUT
User avatar
Joined: 23 Jul 2020
Last visit: 26 May 2024
Posts: 147
Own Kudos:
31
Given Kudos: 30
Location: India
Concentration: Entrepreneurship, Marketing
Schools: Ivey '24 (A)
GMAT 1: 700 Q49 V35
Schools: Ivey '24 (A)
GMAT 1: 700 Q49 V35
Posts: 147
Kudos: 31
Industrialization and modern methods of insect control have improved 10 Oct 2021, 11:58
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi sayantanc2k

Hope you re doing good. Can you help in couple of things ?

1) Do you think usage of which is wrong in option C? I'm doubtful because of the verb HAVE, which should refer to a plural noun pollutants in this case
2) What kind of meaning error are we encountering by misplacing modifier at the same time in C?
3) Why is B preferred over C? Don't you think while is used in temporal sense? While & at the same time : shouldn't they be redundant.
User avatar
ExpertsGlobal5
User avatar
Experts' Global Representative
Joined: 10 Jul 2017
Last visit: 22 Apr 2026
Posts: 6,216
Own Kudos:
6,172
Given Kudos: 44
Location: India
GMAT Date: 11-01-2019
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 6,216
Kudos: 6,172
Industrialization and modern methods of insect control have improved 22 Oct 2021, 07:29
Kudos
Add Kudos
Bookmarks
Bookmark this Post
CRACKGMATNUT
Hi sayantanc2k

Hope you re doing good. Can you help in couple of things ?

1) Do you think usage of which is wrong in option C? I'm doubtful because of the verb HAVE, which should refer to a plural noun pollutants in this case
2) What kind of meaning error are we encountering by misplacing modifier at the same time in C?
3) Why is B preferred over C? Don't you think while is used in temporal sense? While & at the same time : shouldn't they be redundant.
Show more

Hello CRACKGMATNUT,

We hope this finds you well.

Having gone through the question and your queries, we believe we can help resolve your doubts.

In order:

1) In Option C, the use of "which" is incorrect, as it is used to refer to information that is vital to the core meaning of the sentence -- that the 100,000 dangerous chemical pollutants have gone virtually unregulated since they were developed; please remember, “that” is used to provide information needed to preserve the core meaning of the sentence, and the “comma + which” construction is used to provide extra information.

2) The construction "introduced some 100,000 dangerous chemical pollutants at the same time" incorrectly implies that all 10,000 chemical pollutants were released at the same time; the intended meaning is that industrialization and modern methods of insect control have improved the standard of living around the globe, and at the same time, they have introduced some 100,000 dangerous chemical pollutants.

3) You are correct that the use of "while" alongside "same time" is redundant, as they are both used to indicate that the given actions are simultaneous, however, redundancy is NOT a deal-breaker on the GMAT. Redundancy/Awkwardness is the least serious of all flaws on GMAT sentence correction; an answer choice can easily be redundant but still the right answer if the other options have concrete errors. Redundancy can only be used to eliminate an answer choice if it is otherwise error-free, and there is a more concise answer choice. In this case, C has clear meaning and modifier errors that call for its outright elimination.

To understand the concept of "Which" Versus "That" on GMAT, you may want to watch the following video (~2 minutes):


All the best!
Experts' Global Team
User avatar
tkorzhan1995
User avatar
Joined: 16 Oct 2021
Last visit: 30 Aug 2022
Posts: 115
Own Kudos:
16
Given Kudos: 22
Location: Canada
Posts: 115
Kudos: 16
Industrialization and modern methods of insect control have improved 25 Apr 2022, 09:48
Kudos
Add Kudos
Bookmarks
Bookmark this Post
GMATNinja, can you please clarify on the basis of what we should eliminate A?
User avatar
GMATNinja
User avatar
GMAT Club Verbal Expert
Joined: 13 Aug 2009
Last visit: 22 Apr 2026
Posts: 7,391
Own Kudos:
70,798
Given Kudos: 2,129
Status: GMAT/GRE/LSAT tutors
Location: United States (CO)
GMAT 1: 780 Q51 V46
GMAT 2: 800 Q51 V51
GRE 1: Q170 V170
GRE 2: Q170 V170
Products:
GMAT Club Tests
Expert
Expert reply
GMAT 2: 800 Q51 V51
GRE 1: Q170 V170
GRE 2: Q170 V170
Posts: 7,391
Kudos: 70,798
Industrialization and modern methods of insect control have improved 03 May 2022, 06:26
Kudos
Add Kudos
Bookmarks
Bookmark this Post
tkorzhan1995
GMATNinja, can you please clarify on the basis of what we should eliminate A?
Show more
Take another look at (A):

Quote:
Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.
Show more
Notice that "having" follows a clause and a comma, so it should be describing the entire previous clause. But that doesn't make sense here. The absence of regulation isn't the result of improving the standard of living around the world!

The only thing that could have gone unregulated is the noun "pollutants," so it's more appropriate to use a noun modifier to describe those pollutants.

That's exactly what we get in (B): "chemical pollutants that have gone virtually unregulated."

If (A) has a modifier problem and (B) fixes that modifier problem, (B) is better.

I hope that helps!
User avatar
VIGHNESHKAMATH
User avatar
Joined: 28 Sep 2021
Last visit: 21 Nov 2022
Posts: 146
Own Kudos:
54
Given Kudos: 259
Posts: 146
Kudos: 54
Industrialization and modern methods of insect control have improved 09 Jun 2022, 01:59
Kudos
Add Kudos
Bookmarks
Bookmark this Post
paeagain
Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.


(A) while at the same time they have introduced some 100,000 dangerous chemical pollutants, having

(B) while at the same time introducing some 100,000 dangerous chemical pollutants that have

(C) while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have

(D) but introducing some 100,000 dangerous chemical pollutants at the same time that have

(E) but at the same time introducing some 100,000 dangerous chemical pollutants, having


Show Spoiler
https://www.nytimes.com/2000/11/28/science/negotiators-focus-on-dirty-dozen-pollutants.html

Industrialization and modern insect control have improved the quality of life around the globe, but they have also added some 100,000 chemical compounds that, some scientists worry, could affect the health of people and wildlife. These persistent organic pollutants, known as POP's, have gone virtually unregulated since they were developed more than 50 years ago.
Show more


Is it acceptable to say that ''while'' doesn't demand parallelism, but ''but'' demands parallelism? Thus, Option D and E breaks the parallelism rule, which is, however, not applicable for ''while'' construction.

Thank You
Vighnesh
User avatar
EducationAisle
User avatar
Joined: 27 Mar 2010
Last visit: 22 Apr 2026
Posts: 3,906
Own Kudos:
3,586
Given Kudos: 159
Location: India
Schools: ISB
GPA: 3.31
Expert
Expert reply
Schools: ISB
Posts: 3,906
Kudos: 3,586
Industrialization and modern methods of insect control have improved 09 Jun 2022, 03:39
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Good observation. As many experts have pointed out, while is just a subordinating conjunction.
User avatar
Vatsal7794
User avatar
Retired Moderator
Joined: 17 Mar 2021
Last visit: 12 Oct 2025
Posts: 246
Own Kudos:
127
Given Kudos: 123
Location: India
Schools: IIMB EPGP'25 Schulich Sep'24 intake Fisher '26 ISB '25
GMAT 1: 660 Q44 V36
GPA: 3.5
Schools: IIMB EPGP'25 Schulich Sep'24 intake Fisher '26 ISB '25
GMAT 1: 660 Q44 V36
Posts: 246
Kudos: 127
Industrialization and modern methods of insect control have improved 19 Apr 2023, 21:38
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi Experts

GMATNinja KarishmaB MartyTargetTestPrep



Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.


(A) while at the same time they have introduced some 100,000 dangerous chemical pollutants, having

(B) while at the same time introducing some 100,000 dangerous chemical pollutants that have

(C) while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have

(D) but introducing some 100,000 dangerous chemical pollutants at the same time that have

(E) but at the same time introducing some 100,000 dangerous chemical pollutants, having

Hi Experts

GMATNinja KarishmaB MartyTargetTestPrep



Why option C is wrong?
Which can modify checmical pollutants so that is not wrong
Is there a meaning change between B and C?
and Is there any grammatical mistake in option C?
User avatar
Raman109
User avatar
Joined: 17 Aug 2009
Last visit: 28 Jul 2025
Posts: 706
Own Kudos:
212
Given Kudos: 33
Posts: 706
Kudos: 212
Industrialization and modern methods of insect control have improved 25 Sep 2023, 04:39
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.

Option Elimination -

"While" can be used to introduce participle phrases. "While" connects the "participle phrase" to the main clause of a sentence, indicating a simultaneous or contrasting action. Here, "simultaneous" action is important. When "While" is used to introduce a participle phrase, it indicates that the action described in the participle phrase is happening at the same time as the action in the main clause.
For example, While waiting for a bus, Sarah read a book. Or John Sang a song while playing a guitar. Or a contrasting action at the same time e.g. While cooking dinner, she listened to music.

Unlike "But," "while" can be used to introduce subordinating clauses or participle phrases.

(A) At the same time, they have introduced some 100,000 dangerous chemical pollutants, having the first "they" refer to "Industrialization and modern methods" while the 2nd "they" refers to "chemical pollutants." For "having," normally, the structure is "Having finished his work, John went for a walk" - the action of finishing work happened before John went for a walk. Present perfect participle is used to indicate an action that occurred before another past action (different from past perfect - in past perfect, the action has been completed in the past before another past action, but in present perfect participle, the effect of that action (that occurred before another past action) is present). Here, after "Having won," there is no other action.

Here, "having" while making sense with the "introduced some 100,000 dangerous chemical pollutants" doesn't make sense with "Industrialization and modern methods of insect control have improved the standard of living around the globe." So two issues, "they" and "having."

(B) while at the same time introducing some 100,000 dangerous chemical pollutants that have - - Here, the introduction of some 100,000 dangerous chemical pollutants has been happening at the same time Industrialization and modern methods of insect control have improved the standard of living around the globe. So the use of while is correct. The use of "that" is okay to introduce the essential information.

(C) while they have introduced some 100,000 dangerous chemical pollutants at the same time, which have - here there are a couple of issues. To show the simultaneous nature, we need a participle phrase. Moreover, to some extent, the use of "they" is ambiguous. They can refer to "Modern methods" or "Industrialization" and "Modern methods." Also, which can either refer to time or pollutants, though reference to pollutants makes more sense. Additionally, "At the same time" is a misplaced modifier because "Modern methods" or "Industrialization" didn't introduce the pollutants in one single moment just like that. The sentence means that as "Modern methods" or "Industrialization" improved the living standards, they also introduced chemical pollutants (in the same 50 to 100 years time).

(D) but introducing some 100,000 dangerous chemical pollutants at the same time that have - unlike "while" but needs a clause after it. Wrong.

(E) but at the same time introducing some 100,000 dangerous chemical pollutants, having - unlike "while" but needs a clause after it. Wrong.
   1   2 
Moderators:
GMATNinja
GMAT Club Verbal Expert
7391 posts
AbhishekP220108
499 posts
bhanu29
358 posts