4. Write down a/an or some in this rule Countable nouns (what we can count): Uncountable nouns (what we can't count): + countable nouns in the singular: apple, tomato, water (not: a water) banana, potato, onion sugar (not: a sugar) + countable nouns in the plural: juice (not: a juice) three/ apples, five/ flour (not: a flour) tomatoes, two/ bananas, six/ salt (not: a salt) potatoes, four/ onions oil (not: an oil)