Proponents of artificial intelligence say they will be able to make co

We’ve had a few QOTDs lately that feature dashes, including this one. We also discussed dashes in this YouTube webinar on GMAT punctuation. The short version: for the most part, you really don’t want to worry too much about the dashes, since the presence or absence of a dash will almost never be the deciding factor on actual GMAT questions. There are almost always more important things going on in GMAT SC questions that include dashes – and this one is no exception.


If you completely ignore the dash, you can still eliminate (A) quickly and easily. The word “or” is a parallelism trigger, suggesting that we have a list of several items, and those items need to be structurally and logically parallel.

But in this case, they definitely aren’t parallel: “computers that will be used to diagnose equipment breakdowns, deciding whether to authorize a loan, or other purposes such as these…” That’s a hot mess: “to diagnose” is a verb, “deciding” is presumably a noun (gerund), and “other purposes” is also a noun… but even then, it seems like we would need a “for” in front of “other purposes.” Clearly a mess, and that’s enough to eliminate (A).

A far less important issue: the phrase “such as these” seems like a waste of words. I don’t think it’s WRONG, exactly, and I wouldn’t eliminate (A) based on that issue alone. But it’s not awesome.

For whatever it’s worth: I’m OK in principle with the beginning of the underlined portion. The word “does” has plenty of uses in English, but in this case (and in this one), it basically replaces a verb (sort of like a pronoun, but for verbs). So we have “…computers that can… reason as an expert [reasons].” That makes sense.

I’m also OK with the use of the dash, just in case you’re wondering about that, too. The stuff after the dash just gives us a more detailed description of the computer. Fair enough.

Anyway, the parallelism issue IS a really big problem, so (A) is definitely out.


The parallelism is better in (B): “purposes such as diagnosing… or deciding…” Looks much better than (A)!

The problem is the word “which.” In most cases, “which” begins a phrase that modifies the preceding noun – or, at the very least, a noun that’s in really, really close proximity to the phrase beginning with “which.” And in this case, “which may be used for purpose such as diagnosing equipment breakdowns…” seems to be modifying “as an expert does”, and that makes no sense at all. The phrase beginning with “which” needs to describe the computer, not the phrase “as an expert does.”

So (B) can be eliminated.


The parallelism is also really good in (C): “purposes such as diagnosing… or deciding…” Great. And as discussed in (A) above, the dash is also completely fine, since the thing that follows is just a nice description of the computer.

You might be wondering about the use of “like” here. And as you probably know, “like” is generally used to compare two nouns on the GMAT, and “as” is used in situations like these to compare two nouns performing two actions. Consider the following:

1. Like a moldy piece of fruit, Donald Trump has fine orange hair. → correct, since the noun “a moldy piece of fruit” is being compared with another noun, “Donald Trump”, and “like” compares two nouns

2. Like a moldy piece of fruit does, Donald Trump has fine orange hair. → wrong, since the sentence is now structured as “like (noun verb), (noun verb)”, so we’re comparing two clauses (i.e., two nouns with two verbs) – and “like” can only compare two nouns, not two clauses

3. As a moldy piece of fruit does, Donald Trump has fine orange hair. → correct, since we can use “as” to compare two clauses (two nouns with two verbs)… even if it sounds kinda goofy

So it turns out that the use of “like” in (C) is fine: we’re comparing “computers” with “an expert”, and both of those things are nouns, as they are in example #1. (Note that the use of “as” in (A) was also acceptable, because “as” was used to compare two nouns with two verbs: “computers can reason… as an expert does…” That's the same setup as example #3.)

Anyway, I don’t see any problems in (C), so let’s keep it.


The first “like” is fine (“like an expert”), as discussed in the explanation for (C). The second “like”, however, is a problem: the GMAT generally frowns upon the use of “like” to introduce examples, and “such as” is generally preferred. (At least one official exception exists, but “like” is used to introduce examples in all five answer choices, so it’s a non-issue in that case. In every official question that gives us a choice between “like” and “such as”, “such as” is correct.)

There are other problems with (D). The phrase “whether or not” is generally considered redundant on the GMAT, and has never appeared in a correct answer, at least not to my knowledge. There’s also a modifier placement problem: the phrase “the use of which…” seems to modify “an expert”, and that makes no sense, since “an expert” is not being used for “the diagnosis of equipment.”

So we have plenty of good reasons to get rid of (D).


This one is a hot mess. “Whether or not” is generally considered redundant, as we mentioned in (D). “Or the like” makes no sense at all, and I can’t imagine that the GMAT would ever be OK with that phrase. And the parallelism is spectacularly bad: “to be used to diagnose equipment breakdowns, deciding whether to authorize a loan or not, or the like.”

So we can eliminate (E), and we’re stuck with (C).