The GMAT Verbal section overall tends to focus less on individual words and more on the meanings of whole sentences. When comparing the GRE vs the GMAT, vocabulary is essential on the GRE, but students need worry considerably less about vocabulary on the GMAT. If GRE Verbal tests words, GMAT Verbal tests sentences.
The GMAT Sentence Correction expects you to recognize well-constructed sentences. What is a well-constructed sentence? The title, a line from the fourth of the Four Quartets by TS Eliot, gives Eliot’s rather fanciful description of a well-constructed sentence. Let’s be a little more practical.
Of course, good grammar is essential. The GMAT will expect you to have subjects and verbs agree, to use correct tenses, and to recognize the difference of that vs. which. Every nugget of grammar has to be correct, but that’s just the start.
By way of analogy, part of a city planner’s job is to make sure every traffic light in a city is working, but getting each individual light working is only part of the challenge. An effective city planner has to think about “higher level” issues — timing of the lights, patterns of congestions, etc. How does the whole picture of city traffic, the “complete consort,” fit together?
Similarly, the GMAT expects you to analyze sentences not just at the level of grammar but at the higher levels of syntax and meaning. Parallelism is a perfect example. It’s hard to define parallelism precisely because it higher level — we can put individual words in parallel (noun, verbs, adjectives, etc.) or, as is much more typical for the GMAT, we can put entire phrases and clauses in parallel. If we have structure such as “not only [phrase #1] but also [phrase #2]”, it’s not enough that each individual phrase be free of grammar mistakes —- the two phrases must “match” (e.g. both participial phrases, or both infinitive phrases). Parallelism is about whether different parts are “dancing together.”
A very different issue of words “dancing together” concerns idioms. How important are idioms for GMAT Sentence Correction? Very! Here, we mean idioms in the sense of which words “belong” with each other. For example, we would say “an ability to do X”, not “an ability for doing X” or “an ability in doing X.”
Higher level issues extend to logical problems, such as misplaced modifiers or pronouns with unclear antecedent. Finally, the sentence overall must be work rhetorically — it must be unambiguous yet succinct, overall making a direct and powerful statement. That, indeed, is the “complete consort dancing together”!
Part of achieving a good score on the GMAT entails mastering this hierarchy of sentence-construction skills. How you learn this stuff? It’s important to find a tried and true GMAT study schedule, and to avail yourself of the best GMAT material.
It’s important to read high-brow material, such as the Economist magazine. With good materials and practice, this is a “dance” you can learn!