BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
GMATBootcamp Starts Sep 21
Chris Peckover, Target Test Prep GMAT expert
LIVE ONLINE BOOTCAMP

Live Online Bootcamp Class with Top GMAT Expert Chris Peckover

Sep 21 to Oct 9, 2026

Schedule
Mon to Fri · 7:00 to 10:00 PM ET
Included
Live classes + 6 months of TTP OnDemand
  • Boost your GMAT score in less than one month in a live online class
  • 6 months access to TTP OnDemand video courses included
View bootcamp & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

Need help from experts - GMAT Prep question

Expert replies
Post new topic Locked
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 405
Joined: Thu Feb 10, 2011 1:44 amFollowed by: 1 member
Thanked: 3 times
by voodoo_child » Tue Jun 21, 2011 7:49 pm
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 100,000 dangerous chemical pollutants at the same time, and have
d. but introducing some 100,000 dangerous chemical pollutants at the same time that have
e. but at the same time introduce some 100,000 dangerous chemical pollutants, having

I read why b) is correct. However, I am not able to understand how 'improved' and 'introducing' are parallel. To me have + improved is not a participle but present perfect tense. Any thoughts ?

MGMAT discussion thread: https://www.manhattangmat.com/forums/ind ... -t460.html

I am not sure why this question was not raised. I believe that I am missing some concept.

e..g I have done my homework five times. => Have done = present perfect tense

Thanks
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Sentence Correction |
User avatar
Legendary Member
Posts: 1255
Joined: Fri Nov 07, 2008 2:08 pmFollowed by: 90 members
Location: St. Louis
Thanked: 312 times

by Tani » Tue Jun 21, 2011 8:37 pm
The use of "while" calls for the "ing" form of the verb. For example "he can sing while chewing gum", or "she was texting while driving". (The latter is practically a no-no, but grammatically correct.)
Tani Wolff
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 461
Joined: Tue May 10, 2011 9:09 amFollowed by: 3 members
Location: pune
Thanked: 36 times

by amit2k9 » Wed Jun 22, 2011 2:41 am
between A and B.

A having gone ....they .... the usage of they does not have a clear antecedent.They can refer to either Indus.. and mod..methods or to pollutants.
More so introducing is a result of the improvement. Hence present participle format is correct.
Voodoo child worked for GMAT,'studying' harder and harder day by day.
So A is POE'ed.

B has the proper usage of participle form and the relative pronoun that form. Hence the OA.
For Understanding Sustainability,Green Businesses and Social Entrepreneurship visit -https://aamthoughts.blocked/
(Featured Best Green Site Worldwide-https://bloggers.com/green/popular/page2)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Locked
• Page 1 of 1