I'm having trouble articulating what it is I'm looking for, so I'll start with an example.
Candy is delicious.
Candies are delicious.
Vegetables are delicious.
Fruit is delicious.
So, I guess, when referring to a general category or group of things, are there any rules for which ones become plural, which remain singular, and which can be expressed either way?
I was trying to explain to a student why you'd say "prepositions are challenging to learn", and not, "preposition is challenging to learn", and I've come up short.
Any insight would be welcome!