In her book it states that the SAT will often incorrectly pair two singular nouns connected by and ( a structure known as a compound subject) with a singular verb.
Usual syntax : A park a and a lake (runs) along the Loup Canal.
Unusual syntax: Along the Loup canal (runs) a park and a lake.
Shouldn’t the verb be “run” because you have a plural subject?
Yes that is the point. Because the in the unusual syntax it is harder to spot the error and she is showing you an example.
It’s worth noting that this is one of many cases in which standardized tests follow grammar manual rules that have no relationship to the actual English language. In the English language as it resides in the brains of its speakers (which, let’s face it, is the only place it can be), for at least the vast majority of those speakers, the word would generally be runs.
Really, the only way to approach these sorts of grammar-gotcha questions, in my opinion, is to pretend that you’re taking a test on a foreign language that is almost the same as, but not quite the same as, English.
That language is called Standard Written English, and it’s not exactly news that it doesn’t resemble Common Spoken English. Any test on the latter, in fact, would be far, far worse, since there are innumerable regional variations and dialects. Descriptivism has (rightly) won out in the halls of academia, but it’s an impossible benchmark for a standardized test.
The problem with that, however, is that the usage manuals themselves don’t agree—so test-takers are left, as often as not, flipping a coin and hoping it lands on the same side as the test-maker’s preferred manual.
The test doesn’t really include any principles that are particularly controversial among usage guides (whether “none” is singular/plural, for example). Test-takers shouldn’t have to guess at all because the tests have been very consistent in what they’re looking for.