Question

the monkeys ate cherries and mangoes convert to singular

Answer 1

The monkey ate Charrier and mango

Answer 2

The sentence given is in plural form that is the monkeys ate cherries and mangoes.  

So, the plural form of the sentence will be written in the following way.

“The monkey ate cherry and mango.”

Monkeys become monkey

Cherries become cherry and,

Mangoes become mango in singular form when changed from plural form.