Another question on countable versus uncountable nouns.
There is no such thing as a hot-chocolate, just as there is no such thing as a single unit of water. You can have a cup of hot-chocolate, because cups are countable. In saying "I am sipping a hot-chocolate", what you are really saying is "I am sipping a cup of hot-chocolate". This can be made clearer by considering what happens if you add more hot-chocolate to the cup. Do you then have hot-chocolates? Nope, you still have a single hot-chocolate.
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