There are five kinds of nouns:

Common nouns, collective nouns, material nouns, proper nouns, and abstract nouns.
What kinds of nouns is 'hour'?
It's a common noun, so it is a countable noun. Therefore we have to use many before hours. For example, how many hours do you watch TV every day?

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Is my explanation grammatical? I'd like to explain about nouns.

There are five kinds of nouns:

common nouns, collective nouns, material nouns, proper nouns, and abstract nouns.
What kind of noun is 'hour'?
It's a common noun, so it is a countable noun. Therefore<~~add comma we have to use 'many' before 'hours.' For example, how many hours do you watch TV every day?

Corrections are in bold. Overall, you did well.

=)

which of these are proper nouns Cummings, research,time

Yes, your explanation is grammatically correct. You accurately identified "hour" as a common noun and explained that it is countable. You also provided an example sentence using the correct determiner "many" before "hours." Good job!

Your explanation is mostly accurate and grammatical. However, there is a small error in your statement about 'hour' being a countable noun.

In English, 'hour' is actually considered an uncountable or non-count noun. Uncountable nouns, also known as mass nouns, are nouns that cannot be separated or counted individually.

To correct your explanation, you can say:

"It's a common noun, but more specifically, 'hour' is an uncountable noun. Therefore, we don't use 'many' before 'hours.' Instead, we use 'much.' For example, how much time do you spend watching TV every day?"

By using 'much' instead of 'many,' you acknowledge that 'hour' is an uncountable noun.