1. In both sentences particular sorts of cheese are mentioned,
so the noun cheese has become a class countable one.
2. Material uncountable nouns used in a general sense (food
in this case) take no article. The presence of a descriptive attribute
good makes no difference.
3. Snack is a countable noun used as an attribute to foods
which is also countable because it denotes different sorts of
food. Popcorn is an uncountable noun of material. Since it is
used in a general sense no article is used. A treat is a class noun
used with the indefinite article in its classifying function.
4. Lunch is a class noun. As it is used with a descriptive attribute
very fancy it takes the indefinite article in its classifying function.
Meats is a countable plural noun here because it denotes
different kinds of meat. A salad is also a class countable noun as
it denotes a particular sort of salad. As such it is used with the
indefinite article in its classifying function.
5. In the first sentence the material noun wine is used in its
general sense, so it is uncountable, takes no article and is used
with a singular verb. In the second sentence the noun wines
denotes various sorts of wine so it is countable and plural.
6. A wine denotes a particular sort of wine, so it is countable
and can take the indefinite article.
7. See 5, the second sentence.
8. See 5, the second sentence.
9-10. See 5. Vegetable (9) and Jruit (10) are material nouns
used as attributes.
11. A salad denotes a particular sort of salad, so it is countable.
Fruit is an uncountable noun of material used as an
attribute.
12. Two teas mean two cups of tea, and a coffee denotes
a cup of coffee. When one speaks of portions of tea, coffee,
beer, salad, etc. these material nouns become class countable
ones and can be used with numerals or with “a” meaning
“one”.
13. Chicken here is not a bird but its flesh which one eats as
food, so it is an uncountable noun of material. Fruit is an
uncountable material noun used attributively. Fruil here is a singular
invariable noun. The same applies to toast which unlike
fruit is always singular.
14. See 1.
15. Different sorts of soup are mentioned so the noun
becomes a class countable one. A particular kind of broth is
mentioned, so it is countable and can take the indefinite article.
Teas mean different sorts of tea, so the noun has also become a
class countable one.