Hi Nidhs,

The answer choice E is a victim of 'Superficial parallelism'.
The usage of the idiom 'Not only..but also' demands that the structure between the two be parallel.

a) not only add convenience stores but also combine with major fast food chains to build :
Not only add ...but also combine... parallel so CORRECT.

b) not only add convenience stores but also they combine with major fast food chains to build
Not only add ...but also they combine... not parallel so INCORRECT.

c) are not only adding convenience stores but also in combination with major fast-food chains they build
Not only adding ...but also in combination ... not parallel so INCORRECT.

d)add not only convenience stores, but also combining with major fast-fod chains to build
add Not only ...but also combining ... not parallel so INCORRECT.


e)are not only adding conveneince stores, but also in combining with major fast-food chains they build
The answer choice E is a victim of 'Superficial parallelism'. This choice is trying to make the verbs parallel with the verb 'Undergoing' by adding 'ing' at the end. Note if you chose this you are actually splitting the sentence at the

Gasoline marketing is -undergoing major changes as stations
-adding
-combining
Definitely this usage is not correct.
From the figure you might have understood that you have to split at 'stations'


Gasoline marketing is undergoing major changes as stations often
- not only add convenience..
- but also combine...

You see now the structure is parallel.

Hope this helps

Thanks
Komal

nidhs, another way of narrowing down the answer is look at the last word of the underlined part, this has to connect it to the following part of the sentence. In this case you can rule out C & E, because "they build" is wrong, it is supposed to say "to build", and after that you have 3 to choose from.

Nidhs wrote:Gasoline marketing is undergoing major changes as stations often not only add convenience stores but also combine with major fast food chains to build complexes where customers can shop and eat as well as buy gasoline.
a) not only add convenience stores but also combine with major fast food chains to build
b) not only add convenience stores but also they combine with major fast food chains to build
c) are not only adding convenience stores but also in combination with major fast-food chains they build
d)add not only convenience stores, but also combining with major fast-fod chains to build
e)are not only adding conveneince stores, but also in combining with major fast-food chains they build

The OA is A. I chose E. Can someone tell me why a simple present
is used

Correct idiom: not only X but also Y
X = some form of verb "add"
Y = some form of verb "combine"

X and Y should be parallel.

A - yes they are
B - no (add, they combine)
C - no
D - no (Add, combining)
E - in combining is incorrect.