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Mentally Use the Colon to Clarify Parallel Construction

GMAT sentence correction parallelism strategy trick colonOne of the six major points of English grammar tested on GMAT sentence correction questions is parallelism, otherwise known as parallel construction. (For detailed teaching on all six grammar categories, see our “Sentence Correction – Part 2” lesson).

The idea is simple: When two or more things or ideas are being listed, they must be introduced in the same grammatical form for consistency.

For example, consider the following erroneous sentence:

The production manager was asked to write his report quickly, accurately, and in a detailed manner.

Sounds pretty good, doesn’t it? (Although I told you up front that it was erroneous, so hopefully it didn’t sound too good!)

But consider the grammatical form of the three things being listed that describe how the production manager was asked to write his report. The first is quickly, an adverb. The second is accurately, also an adverb. Yet the third? “In a detailed manner” is a prepositional phrase, not an adverb, and therefore doesn’t follow parallelism with the rest of the sentence. On the GMAT, it would need to be changed to an adverb as well, perhaps something such as thoroughly.

Okay, so that was pretty easy. But what about harder questions where parallel construction may not be quite so obvious?

Consider this example:

By providing such services as mortgages, home improvement loans, automobile loans, financial advice, and staying within the metropolitan areas, Acme Bank has become one of the most profitable savings banks in the nation.

(A) financial advice, and staying
(B) financial advice, and by staying

(C) and financial advice, staying
(D) and financial advice, and staying
(E) and financial advice, and by staying

Here’s a clever trick to help you master harder parallelism questions on the GMAT: Mentally insert a colon where you believe the list of items/thoughts begins! Then number each of the items in the sequence to make sure it makes logical sense.

In the example above, where does the list of “things” begin?

Well, you get extra credit if you noticed that there are actually two lists in this sentence, and therefore two aspects of parallel construction that we need to pay attention to. Let’s go ahead and start with the easier-to-detect list. It’s the list of services that Acme Bank provides, right? So what are those services?

To help clarify it for you, let’s apply the colon trick I mentioned earlier. The start of services that Acme Bank provides starts after the word “as”. So it would look something like this:

By providing such services as: 1) ________________, 2) ________________, 3) ________________, etc….

So what are those services? And how many services are there? There are four of them, and they are as follows (for now we’re still just looking at that first part of the sentence):

By providing such services as: (1) mortgages, (2) home improvement loans, (3) automobile loans, and (4) financial advice….

Now, notice what I automatically did? I inserted the word “and” before the fourth and final item in the list, which is a grammatical necessity. Since it’s not currently in the original sentence, and now that we recognize that it must be there, we can go to the answer choices and eliminate any answers (including the original version of the sentence in answer choice A) that don’t correctly insert that word “and” before “financial advice.” So answers A and B are out.

But now what about the larger framework of the sentence? I mentioned that there are actually two lists in this sentence. Where’s the second one? It’s the things that Acme Bank has done to become one of the most profitable savings banks in the nation. And the bank has done two things to achieve that status. The easiest way to see that is to invert the sentence and then, again, to mentally insert a colon before introducing those two things. It would look something like this:

Acme Bank has become one of the most profitable savings banks in the country: A) ______________, and B) _______________.

The first way it has done that is “by providing such services as ….,” which is how the original sentence begins. In other words, that first list we just looked at is actually a sub-list within this first thing Acme Bank has done to become so profitable. Yet, in the larger framework of the sentence, providing those services is just one of the two major things Acme Bank has done to become one of the most profitable savings banks in the country.

The second thing is that it has stayed within the metropolitan areas.

So to summarize, we might abridge the larger parallelism framework as follows (inserting that mental colon, of course!):

Acme Bank has become one of the most profitable savings banks in the country: (A) by providing such services as …., and (B) by staying within the metropolitan areas.

Again, notice what I automatically did when I re-wrote this condensed version of the sentence? I inserted the word “by” before part B of the lists so that it matches the grammatical form of part A. Thus, the correct answer must do the same, and only answer choice E does that. So E is the correct answer.

Now, let me clarify that last point. How did I know to insert the word “by” before “staying within the metropolitan areas”? Because the first item in the list (“providing such services…”) is introduced that way. That’s how the original sentence begins. And since that part is in the un-underlined portion of the sentence, it dictates what must happen in the underlined portion. For more on that key understanding of GMAT sentence corrections, see my article “Beware Confirmation Bias on GMAT Sentence Corrections”.

So there you have it! Parallel construction isn’t all that hard on the GMAT once you clearly delineate the components of the list(s) in question. But that’s easier said than done, especially on harder questions. Now that you’re armed with this colon trick, however, hopefully it will become easier for you and empower you to dominate the GMAT!

Confused? Like what you see? Post your questions/comments in the comments area below!