Some nouns have the same singular and plural form. For example:
(one sheep, two sheep)
- There was one sheep in the field.
(singular verb/was – one sheep)
There were five sheeps in the field.
There were five sheep in the field.
(plural verb/were – five sheep)
- What is your favourite aircraft?
(singular verb/is – asking about one aircraft, your number 1)
What are your favourite aircrafts?
- What are your favourite aircraft?
(plural verb/are – asking about many aircraft, your top 10)