UPDATE: You can find this blog and others about idioms in our new GMAT Idiom eBook!
Sort out the bedeviling distinctions between these two words that confound many on GMAT Sentence Correction
Start by attempting these two questions on your own. I will discuss the solution later in the post.
1) Balancing the need for sufficient food supplies with what constitutes a manageable load to carry was undoubtedly a concern at times for many ancient hunters and gatherers, like that for modern long-distance backpackers.
(A) like that for modern long-distance backpackers
(B) as that of modern long-distance backpackers
(C) just as modern long-distance backpackers do
(D) as do modern long-distance backpackers
(E) as it is for modern long-distance backpackers
2) The Book of Kells, an illumination of the four gospels produced in eighth century Ireland, a demonstration of what many consider the pinnacle of Celtic knotwork art and incorporating such foreign pigments like indigo from India and lapis lazuli from Afghanistan.
(A) a demonstration of what many consider the pinnacle of Celtic knotwork art and incorporated such foreign pigments like
(B) demonstrated what many consider the pinnacle of Celtic knotwork art and the incorporation of such foreign pigments like
(C) demonstrated what many consider the pinnacle of Celtic knotwork art and incorporating foreign pigments as
(D) demonstrated what many consider the pinnacle of Celtic knotwork art and the incorporation of such foreign pigments as
(E) demonstrated what many consider the pinnacle of Celtic knotwork art and incorporated such foreign pigments as
Part One: Comparisons
For a variety of reasons, the GMAT loves comparisons on the Sentence Corrections questions. First of all, the terms of comparisons must be in parallel, and the GMAT loves parallel structure. Furthermore, the comparisons on the GMAT are almost never (single word thing) vs. (single word thing), but, rather, nouns modified by extended phrases and clauses, so that one has to read carefully to sort out which two things are being compared. Finally, they love distinctions like the “like” vs. “as” distinction.
The word “like” is a preposition, whose object is a noun, so it’s used for comparing noun-to-noun. The word “as” is a subordinating conjunction, which is followed by a full noun + verb clause, so it is used to compare events, actions.
1) Correct: Blue tits, like peacocks, demonstrate strong sexual dimorphism.
2) Incorrect: Blue tits, as peacocks, demonstrate strong sexual dimorphism.
3) Incorrect: Mahler died after composing his ninth symphony, like Beethoven and Dvorak had before him.
4) Correct: Mahler died after composing his ninth symphony, as Beethoven and Dvorak had before him.
If the comparison is simply between nouns, use “like.” If the comparison involves a full subject + verb clause, use “as.”
In sentence #1 above, (A) & (B) construct the comparison so that it focuses on a noun, the pronoun “that”, so “like that” would be correct and “as that” would be incorrect. Unfortunately, both of these are merely phrases, not the full subject + verb clause that would be parallel to the main clause. Answers (C)-(E) all have “as” with a subject & verb, so w.r.t. the “like” vs. “as” question, all three work. Distinguishing among (C)-(E) depends on the parallelism. The verb in the main clause is “was”, a form of the verb “to be” — this balancing “was a concern” — and a proper parallel to a form of “to be” cannot be a form of “to do.” Forms of the verb “to do” can form the proper parallel to almost any action verb, but not a form of “to be.” Both (C) & (D) have “do”, which is incorrect parallelism. Finally, we want to create a parallel to “many ancient hunters and gatherers. Those words are preceded by the preposition “for”, so the parallel term must contain this same preposition. Choice “E” has the correct preposition “for”, the correct “like” vs. “as” structure, and a form of “to be”: it has an elegant structure that is correct and far superior to the other incorrect choices.
Part Two: Examples
The words “like” and “as” are also used in listing examples, but here we have to know a specific idiom. The unadorned “like” is used in colloquial speech, but the word “as” needs the word “such” —
5) Passerine birds like sparrows and swallows, ….
6) Passerine birds such as sparrows and swallows, ….
7) Such passerine birds as sparrows and swallows, ….
Notice, the “such … as” construction may involve the two words next to each other, or (as is far more likely on the GMAT SC!) separated by a word or words followed by an extended modifier. Notice also that the use of “like” for a list of examples is always incorrect on the GMAT.
The second sentence, about the Book of Kells, a work of which I am deeply enamored, explores the “like”/”as”/”such as” split in a list of examples. That sentence gives an example of “foreign pigments”, and the two examples are “indigo from India and lapis lazuli from Afghanistan.” The possibilities are
Incorrect = “foreign pigments like indigo etc.” (none of the answers)
Correct = “such foreign pigments as indigo etc.” (answers (D) & (E))
Incorrect: “foreign pigments as indigo etc.” (missing the word “such”, answer (C))
Incorrect: “such foreign pigments like indigo etc.” (the disastrous “such…like” combination, answers (A) & (B).
That split immediately narrows the choices down to (D) and (E). To finish the problem off, we need to consider the near-ubiquitous issue of parallelism. The words “demonstration/demonstrated” and “incorporation/incorporated” need to be in the same form: in fact, they both need to be verbs, so that the subject “the Book of Kells” has a bonafide verb. The only answer to get all of these correct is (E).
Here’s another SC question for further practice.