Countable Nouns Acting as Non-countable Nouns and Vice Versa

Depending on how they are used, some nouns that are considered non-countable are also used as countable. The following examples show how the same noun can function as both countable and non-countable:

Non-countable	Countable
Some protein was left in the tube.	We have isolated two proteins: hemoglobin and myoglobin.
Water is required of all life forms.	She requested a water with her meal.
Coffee is necessary for all lab personnel.	I'll buy a coffee at Starbucks.
She studied calculus in college.	The patient had a renal calculus.
Film should not be exposed to room light.	A film formed on the side of the flask.

Return to Using Articles or go to Step 3: Using the Definite Article.

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