4. Noncount nouns have no plural:
homework
money
milk
water
pollution
silver
furniture
5. A/AN is for a singular count noun:
a person
a desk
a man
a child
an umbrella
an apple
6. With plural count nouns and non
count nouns, don’t use A/AN.
Use some/any
Some is for affirmative
Any is for negative
A question can use some OR any