Using le, la, les, du, de la, de, des

Question

I've read through the relevant lessons, but I'm still not clear on a few points:

If want to say "He likes cheese" do I say "Il aime le fromage" ? 
What about the negative: "He doesn't like cheese" is it "Il n'aime pas le fromage" ?

Why is "I adore cucumbers" "J'adore les concombres" but
"I eat apples"  "je mange des pommes" ?

What about with "avoir peur" is it "il a peur des chiens" ? 
In the negative would it be "il n'a pas peur de chien". ?

Accepted Answer

Bonsoir Kim,
The following articles are partitive: de, du, de la, and des while these are definite articles: le, la, l' and les. In this phrase: On n'aime pas la musique classique. --> We dont like classical music. (we don't like any classical music)
Elle n'aime pas les bonbons. --> She doesn't like sweets. (she doesn't like any sweets)
So here is another example from a lesson: When things are countable (dogs, cars etc.) and you want to say some, you use des. Il y a des chiens. --> There are some dogs. or There are dogs.

Answer

Bonjour Kim !The difference is whether you're making a general statement or talking about "some" specific things.Il aime le fromage is a statement about cheese in general, so you will use "le"See https://french.kwiziq.com/revision/grammar/use-le-la-l-or-les-before-nouns-when-generalising-definite-articles
In a negative sentence, le, la, l', les remain the same:Il n'aime pas le fromage.When you say J'adore les concombres, you're talking about cucumbers in general - you couldn't say "I love some cucumbers" here, hence the use of les. As for "avoir peur", it's a fixed expression always followed by the preposition de (literally to have fear of), so when used with the definite article les, de + les contract into des :Il a peur des chiens. => He's scared of (the) dogs. See https://french.kwiziq.com/revision/grammar/avoir-peur-de-to-be-afraid-or-scared-of
In the negative, as we said above, les remains the same, so it applies to its contracted form as well:Il n'a pas peur des chiens. 
I hope that's helpful!À bientôt !