I always have many confusions for singular or plural, should the cat be a cat, cats or simply cat:
Human adopted many pets in history, for example cat, dog, etc...
Human adopted cats in history.
What cat do you eat?
What kind of cats do you eat?
I just want to say a thing or a concept called "cat", it's unimportant wether there are many cats or not, but maybe "cat" should be regarded as a collected whole, so "cat" is inherently cats hence it should be cats?
The same for "kind" above.
BTW, I remember there are some special word combinations (maybe using prepositions?) that you don't need "s" after nor "a" before countable nouns, but I can't remember specific details, it would be really helpful that someone makes some such examples. (I assume "what" is one of the example?)