The subject of this sentence is plural ("rules"), but the verb "is" agrees with a singular subject. Changing "is" to "are" corrects the sentence's error. The corrected sentence reads, "The rules posted in the lobby are intended to be guidelines only."

In this sentence, the verb “were” does not agree with the singular subject “frequency.” The corrected sentence reads, "The frequency with which her father was bringing home bushels of raw beets was concerning to Kathy."

In this sentence, the verb does not agree with the subject. The subject “rhododendrons and lilacs” is plural, but “seems” agrees with a singular noun. The corrected sentence reads, "The rhododendrons and lilacs that line the garden path seem out of place in the shadow of the concrete structure."

The subject here is the singular gerund (verbal noun) "doing"—not the plural noun "things." Thus, the main verb should be the singular—"is," not "are."

The subject of the sentence is "spread," which is being used as a singular noun; however, the sentence's verb, "are," agrees with plural nouns, not singular ones. To correct the sentence's error, "are" should be changed to "is."

The subject in this sentece is "Massage and physical therapy." Because the sentence's subject consists of multiple nouns connected by the conjunction "and," it is a compound subject; compound subjects take plural verbs, so "helps," which agrees with singular nouns, is incorrect. The corresponding verb should be "help," not "helps."

It is easy to think that the verb "are" refers to "constituents," but in this case ("The politician, along with his many constituents, are . . ."), the verb refers back to "politician," since "along with his many constituents" is a prepositional phrase. So, the plural verb "are" is incorrect since it refers to the singular "politician," and should be replaced with the singular verb "is." The corrected sentence reads, "The politician, along with his many constituents, is opposed to the new reforms being enacted by the government."

Don't be confused here by the plural nouns "trails" and "parks"—neither of these is the subject of the sentence's main clause; they merely add information about the subject. "Running," may initially seem to be a verb, but here it is functioning as a gerund, a verbal ending in "-ing" that functions as a noun. As such, it is a singular subject and needs to take the singular verb "is," making "are" incorrect.

The verb "does" is used with singular nouns, but in the sentence as it is written, it refers to "types," a plural noun. To correct the sentence's error, we would need to change "does" to "do," or omit "do" completely, as just the "than" is sufficient to make the comparison.

This sentence is about two families (plural) that are successful. The sentence has them becoming the leader (singular) in the region. This discrepancy in number is an error. The corrected sentence reads: The two families developed their farms in friendly competition and eventually became the leaders of the region’s dairy production.