The noun 'krill' is an uncountable noun, a word for collection of small marine crustaceans, often found in large groups in the ocean.
The singular form is it, the plural form is they(subjective) and them (objective).
The word crisis is singular. The plural form of crisis is crises.
The singular possessive form is lesson's.
The singular possessive form is grotto's.
It already is singular. The plural form is louse.
The singular form of the word flagella is flagellum.
Criterion is the singular form of criteria.
The word 'duo' is the singular form; the plural form is duos.
The singular form of the word "señores" is "señor."
That is the singular form; the plural form is those.
The singular form is commando.
'Jackhammer' is the singular form.
The word dog is the singular form.
The singular possessive form of jury is jury's
The word "biopsies" is the plural form of the word. The singular form is "biopsy."
The singular form of Sioux is "Sioux." It is both the singular and plural form of the word.
The singular form of the word "possum" is possum. The plural is possums.