The Editor's Manual
Free learning resource on English grammar, punctuation, usage, and style.
Use “each of” with singular verbs to refer to every one of a group separately. “Each of” may be followed by a plural, gender-neutral pronoun. In spoken English, “each of” is sometimes used with plural verbs to refer to an entire group.
When “each” is part of the subject of a sentence, it is used with singular verbs, except when it follows a plural noun. “Each” may be used with a plural pronoun in an indefinite reference.
Names of decades and centuries (the 1800s, the 1970s, the eighties, the ’90s) are generally considered plural but can also be used with singular verbs.
One of a group is singular (“One of them is” not “are”). But when “one of the” is followed by “who” or “that,” check who is being described: the entire group or one of them.
“Neither,” which means “not either,” negates each of two possibilities individually. Treat it as singular (“neither is”). In informal usage, it sometimes negates both things together and then takes a plural verb (“neither are”).
When the words in a compound subject are joined by “and,” it is plural. When they are joined by “or” or “nor,” the verb should agree with the part closest to it. When phrases like “as well as” are attached to a singular subject, it stays singular.
Data can be a plural noun (“the data are”) or a singular mass noun (“the data is”). As a mass noun, it is used much like the word “information.”