Poetry is an Uncountable Noun or Mass Noun; which means a noun that cannot be used freely with numbers or the indefinite article, and which therefore takes no plural form.
Some examples of such nouns are words like "information", "money" and thus the word "poetry" can be singular or plural based on the context of usage.
Source: Wikipedia - Mass Nouns
The noun 'beats' is plural for the singular 'beat', a rhythmic unit of music or poetry.
The word team is singular; the plural form is teams.
These is plural, this is singular
if a word refers to a single item it is singular. if it refers to lots of things it is plural."Potato" is singular "potatoes" is a plural word."mouse" is singular, "mice" is a plural word."person" is singular, "people" is a plural word.
The word metastasis is singular, metastases is plural.
The word "louse" is singular. The plural form is "lice."
No, the word "list" is singular. The plural form of "list" is "lists."
Caveman is singular. Cavemen is plural.
Verbs cannot be singular or plural. Has is after singular nouns.
It's singular. The plural is cafeterias.
Tool is singular. Tools is plural.
Singular Plural is caterpillars