Question 137·200 Super-Hard SAT Reading Questions·Standard English Conventions
Among the features that distinguish a nineteenth-century observatory's field notebooks from its printed star catalogs _____ beside observations of low-altitude stars; historians propose that the observers used these marks to flag sightings that atmospheric haze might have distorted.
Which choice completes the text so that it conforms to the conventions of Standard English?
When a sentence begins with a prepositional phrase such as “Among the features,” locate the true subject rather than matching the verb to a nearby plural noun. Then analyze any relative construction separately: in a phrase such as “each of which,” the verb agrees with “each,” not automatically with the plural antecedent of “which.”
Hints
Look beyond the opening phrase
The sentence uses an inverted structure. Locate the subject that appears after the blank and identify that subject’s head noun.
Examine the relative construction
In the phrase “each of which,” determine which word serves as the grammatical subject of the following verb.
Step-by-step Explanation
Identify the main subject
The opening prepositional phrase begins with “Among,” and the main subject follows the blank: “a sequence of tiny dots.” Because the head noun “sequence” is singular, the main verb must also be singular.
Identify the subject of the relative construction
In “each of which,” the subject of the verb is the singular pronoun “each.” Although “which” refers to the plural noun “dots,” the verb must agree with “each.”
Apply both agreement rules
The sentence requires a singular main verb agreeing with “sequence” and a singular relative-clause verb agreeing with “each”: “is a sequence of tiny dots, each of which appears.”