Each of us works to keep our environment safe.

The prepositional phrase “of us” is not the subject; it is modifying (giving more information about) the subject. “Each” is the subject.

If you take away the prepositional phrase, you are left with:

Each… (“work” or “works”) to keep our environment safe.

“Each” is singular, so the correct verb is the singular verb “works.”

Clayton is the mechanic who does the repairs.

The word “who” in the sentence refers to one person, Clayton. If you replace the word “who” with “Clayton” or “he,” it is easier to select “does” (“Clayton does…” or “he does…”)

Is either conveyor available?

Even though the question is asking about two conveyors to find out which is available, the word “either” divides the choices – it refers to only one conveyor at a time. Therefore, the subject is singular.

The robotic arm and the soldering tool use fiber optic wiring.

There are two subjects in this sentence (robotic arm and soldering tool), so the subject is plural. The plural subject must be paired with the plural verb “use.”

Tip: When you have two subjects, replace them with the word “we” to make it easier to select the correct verb. For example, in this sentence, you can replace “The robotic arm and the soldering tool” with “We” to form the sentence “We use …”

The inspector or the supervisor files the report.

The word “or” separates the subjects “inspector” and “supervisor.” When two or more subjects are separated, focus on the subject closest to the verb. In this example, the subject closest to the verb is “supervisor.” Because “supervisor” is singular, it requires the singular verb “files.”

Neither James nor the machinists approve the changes.

The word “nor” separates the subjects “James” and “machinists.” When two or more subjects are separated, focus on the subject closest to the verb. In this example, the subject closest to the verb is “machinists.” Because “machinists” is plural, it requires the plural verb “approve.”

Tip: When two or more subjects are separated, try reading the sentence using only the subject closest to the verb. In this example, the sentence would read: “The machinists approve…”

Most facilities except the main office are consolidating printing services.

In this sentence, “most facilities” are doing the action (consolidating), so the subject is plural. The phrase “except the main office” is a prepositional phrase that modifies (gives more information about) the subject, but it is not part of the subject. 

Tip: Take away the prepositional phrase to make it easier to identify the correct verb. In this example, the sentence would read: Most facilities… (“is” or “are”) consolidating printing services.

The number of manufacturing jobs is rising due to the increasing demand for durable goods.

“The number” refers to a specific number, even if the sentence does not tell us what that number is. Because the number is specific, the subject is singular and requires the singular verb “is.”  The  phrase “of manufacturing jobs” is a prepositional phrase that modifies (gives more information about) the subject, but it is not part of the subject. 

Tip: Try removing the prepositional phrase and adding an actual number after the words “the number.” In this example, the sentence could read: The number twelve “is” rising due to…

A number of companies have expanded services to meet the increasing demand.

In this example, “a number” is not specific. It means “many” or “several,” so the subject is plural and requires the plural verb “have.” The phrase “of companies” is a prepositional phrase that modifies the subject, but it is not part of the subject. 

Tip: Try removing the prepositional phrase and using “Many” or “Several” instead of “A number.” In this example, the sentence would read: Many  (“has”) expanded services…