Singular. Plural is: they are, have and do.
Derogatory is an adjective, and has no plural forms.
There are two accepted forms of the noun: adviser and advisor.The plural forms are advisers and advisors.
The plural forms of the noun executrix are executrices or executrixes, both forms are accepted.
The plural form for the noun machine is machines, a regular plural form.A regular plural is a word that forms the plural by adding an -s or an -es to the end of the word.An irregular plural is a word that forms the plural in some other way.
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The plural possessive for the noun forms is forms'.
There are two accepted forms of the noun: adviser and advisor.The plural forms are advisers and advisors.The plural possessive forms are advisers' and advisors'.
plural forms are uteri or uteruses.
Verbs don't have plural forms.
There are two accepted plural forms of the noun vertex: vertices and vertexes.The plural possessive forms are vertices' and vertexes'.
The plural form of thesaurus is "thesauruses" or "thesauri."
Typically you would remove the plural suffix (-s, -es) or change it to the singular form (-y to -ies, -ies to -y) depending on the word. For irregular plurals, there may be specific rules to follow or you may need to consult a dictionary for the singular form.
The plural forms for the singular lumen is lumina or lumens, both are accepted plural forms.
The possessive plural form of "curriculum" is "curricula's".
There are two accepted plural forms for the noun cargo, they are cargoes and cargos.The plural possessive forms are cargoes' and cargos'.
German plural forms are formed irregularly.