Mass nouns such as “water” or “mud” are neither singular nor plural. You can`t say “one water” or “two water,” because it`s all just a continuous object (unless you`re talking about two different water tanks). Mass nouns represent a generic and unknown quantity of what they are. You take a singular verb form. Note: example #1, with which the plural precursor is closer to the pronoun, produces a smoother sentence as an example #2, which forces the use of the singular “to be or her”. But pronouns and precursors can also appear in the same sentence: buzzes and products adopt singular verbs in mathematical equations. Broken expressions vary depending on the meaning. Some words without quantity end in “s”, but also accept singular verbs, since they refer to individual units or entities. .