Non count nouns

Sure, they're correct! The verb agrees in number with the subject of the sentence.

if apple and carrot were singular, are they still correct?

In the singular you will need the word "the".

My favorite fruit is the apple.
My favorite vegetable is the carrot.

These are correct, but people do not usually say them that way. They usually say "is carrots", and so on.

Thanks. So people ask you, "Do you like apples?" I would answer, "Yes, I like apples."

"Do you like apple" as a question would be wrong?

That's right. "Do you like apple" would be wrong. Apples are countable, so the singular "apple" cannot occur without a determiner before it. "the apple", "an apple", "my apple", "this apple" are all fine, but not just "apple". This is true of all countable nouns.

The singular of uncountable nouns, in contrast, may occur without a determiner, as in "I like wine."

Thanks a lot.

I read some talk that you reply about Uncountable words in sentences

I have a wonder.

Which is correct?

" My favorite pet is a cat", "My favorite pet is cats", or "My favorite pets are cats"

Navtive speakers say different answers so That I am so confused.

Please tell me correct answer.

Thankyou.

All three are correct. In every language there are often several ways of saying the same thing, and different people prefer to express themselves in different ways.

Then, do you say that...

"My favorite pet is dogs and cats." or " ~ pets are ~"

"My favorite food is pizza and hamburger"

"My favorite sport is baseball and basketabll." or "My favorite sports are baseball and basketball."

"My favorite subject is English and math." or "My favorite subjects are English and Math."

Are these above all correct?

"My favorite pets are dogs and cats."

"My favorite foods are pizza and hamburgers"

"My favorite sports are baseball and basketabll."

"My favorite subjects are English and math."

"I like pizza better than hamburgers."