Mike MᶜGarry

GMAT Idioms: Compound Prepositions

UPDATE: You can find this blog and others about idioms in our new GMAT Idiom eBook!

Prepositions in English display a powerful diversity of uses. Your preposition knowledge will most certainly be tested on the GMAT. In a previous preposition article, we talked about four prepositions.  Here, we will look at compound prepositions in English.  A compound preposition is a set of two words that, together, function as a single preposition.


Prepositions on the GMAT

A preposition must be followed by a noun, or by something playing the role of a noun.   This latter category includes gerunds and substantive clauses.

1) Prior to composing the early masterpiece Der fliegende Holländer, Wagner composed a few second-rate operas that critics today would consider hardly worthy of him. 

2) According to whoever wrote these inane instructions, we cannot complete the papier mache house without a lathe

In sentence #1, the object of the preposition “prior to” is a gerund phrase, and in sentence #2, the object of the preposition “according to” is a substantive clause.   Incidentally, both of these exemplify idioms involving these prepositions.


The compound prepositions

These seven are the most common compound prepositions in the English language:

According to

As of

Because of

Instead of

Next to

Out of

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Prior to

To some extent it is a matter of debate whether some of them are “compound prepositions” — for example, “prior” is an adjective, so if we were to say “P is prior to Q”, is that an [adjective + preposition] or a compound preposition before Q?  Grammatical purists debate such things.  Because the answer to such questions doesn’t impinge at all on preparing for the GMAT Sentence Correction, I’m just going to plow forward and treat all seven as compound prepositions.  I will explain a bit about the usage of each.  I will not discuss the third — the idiom “because of” — because that was treated in another post.


According to

This structure is almost always used to cite an authority of some kind, either a person (“according to Aristotle“, “according to Vin Scully“, “according to https://magoosh.com/gmat/“, an authoritative body (“according to the Russian Orthodox Church“, “according to the Oprah Magazine“, “according to the Mayberry police force“) or a discipline or body of knowledge (“according to Quantum Chromodynamics“, “according to the Black-Scholes model”, “according to the Charlie Lau school of hitting”).

The object of this preposition always has to be someone who or something that could issue an opinion or support a position of some kind.   Most often, this will be a simple noun, such as the ones cited in this paragraph. However, the object could also be a relative clause indicating an unknown or indefinite subject, as in example #2 above.


As of

This is a very specific idiom.   It is used to indicate the time of some important transition.  The object is always a time of some kind.  The object could be a substantive clause beginning with “when” or “whenever”, although this somewhat unusual construction is unlikely to appear on the GMAT.

3) As of July 1, 1997, Hong Kong has been fully a part of the People’s Republic of China.

4) As of next Wednesday, our stores will no longer carry Eridanus products.

5) As of whenever she returns from work, we will start the party.


Instead of

The structures “instead of” and “in place of” mean essentially the same thing and are interchangeable.  Theoretically, the structure “A instead of B” would be correct if A & B were simple nouns.  Typical mistakes involving “instead of” use the structure “A instead of B” to contrast prepositional phrases or larger grammatical constructions.


That sentence will always be considered incorrect on the GMAT Sentence Correction.

6b) These cookies are sweetened with citrus juices rather than with cane sugar.

The GMAT loves to contrast an incorrect “instead of” structure with a correct “rather than” structure.  The structure “instead of” never seems to appear on the GMAT in instances in which this structure would be correct.


Next to

Literally, this structure indicates physical adjacency: “the lawnmower is next to the shed.”  This use is grammatically correct, but it is typically too simple to appear on the GMAT Sentence Correction.

In colloquial American English, the construction “next to” is used as a synonym for “compared to.”


This will always be considered too informal, and will never be correct on the GMAT.

7b) Compared to Haydn, Mozart had a relatively small output as a composer.

The compared to structure is the proper structure for such comparisons.


Out of

Literally, this construction indicated spatial movement from something enclosed or interior to a wider expanse —– “out of Africa“, “out of the University of Minnesota”, “out of the boondocks.”  Many of these statements are too colloquial for the GMAT.

This construction is also used colloquially to denote “lacking”, as in “out of gas“, “out of breath“, “out of his mind.”  These constructions will never appear on the GMAT.

The words “out of” can be used to denote ratios — “Seven out of ten employees said …” While slightly more formal than the other forms of “out of”, even this is quite unlikely to appear on the GMAT sentence correction.


Prior to

The words “prior to” mean “before”, but there is a big difference.  The words “prior to” function only as a preposition —- the object can only be a noun or something functioning as a noun (gerund or substantive clause).  By contrast, the word “before” can function as a preposition (followed by a noun) or as a subordinate conjunction, followed by a full [noun] + [verb] clause.

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BEWARE — the GMAT doesn’t approve of the structure [preposition]+[noun]+[participial phrase]. The GMAT doesn’t like to cram that much action into a prepositional phrase.  If you want to talk about that much action, use a full [noun] + [verb] clause, not just a preposition.  Also, note: with simple clock times or times of day, the word “before” sounds more natural, and the phrase “prior to” sounds artificial.

8) Before dawn every day, the colonel would jog five miles.

The words “prior to” would sound awkward in this sentence. In the following sentences, notice the subtle changes between the paired sentences.

9a) Before he was 20 years, Mozart was renowned as a virtuoso performer and an accomplished composer.

9b) Prior to his twentieth year, Mozart was renowned as a virtuoso performer and an accomplished composer.

10a) Before Melville published his magnum opus, Moby Dick, he had been financially successful with a couple smaller novels.

10b) Prior to publishing his magnum opus, Moby Dick, Melville was financially successful with a couple smaller novels.

As long as the subject of the “before” clause and the subject of the main clause are the same, the construction “prior to” + [gerund] can be used.   When these two subjects are different, though, problems arise.

11a) Before Shackleton could mount a second Antarctic expedition, Roald Amundsen became the first person to reach the South Pole.




Know the idioms given in bold in this post and learn to identify the incorrect constructions in red.  As always with idioms, read, read, read!   Search for the idioms in this post in context.  You understand English best when you understand it in context.




  • Mike MᶜGarry

    Mike served as a GMAT Expert at Magoosh, helping create hundreds of lesson videos and practice questions to help guide GMAT students to success. He was also featured as “member of the month” for over two years at GMAT Club. Mike holds an A.B. in Physics (graduating magna cum laude) and an M.T.S. in Religions of the World, both from Harvard. Beyond standardized testing, Mike has over 20 years of both private and public high school teaching experience specializing in math and physics. In his free time, Mike likes smashing foosballs into orbit, and despite having no obvious cranial deficiency, he insists on rooting for the NY Mets. Learn more about the GMAT through Mike’s Youtube video explanations and resources like What is a Good GMAT Score? and the GMAT Diagnostic Test.

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