From Wikipedia: The internal combustion engine is perhaps the most common example of a heat engine, in which...

The internal combustion engine = all (general) internal combustion engines. Systems/machine take "the" when they are explained as a thing in general, not a particular example. Am I correct?

How about "iron ore", which is C/U, as a thing in general? Iron ore contains some substances. No article?

  • 1
    You are correct, but iron ore is a substance (an uncountable noun) rather than a thing. Jul 31, 2021 at 15:50
  • Good to hear that. I see. Thank you Kate for your help always.
    – Yamato
    Jul 31, 2021 at 16:40


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