石炭

In a sentence

• 石炭は化石燃料の一種です。

  Coal is a type of fossil fuel.

  Here, '石炭' is used as a noun to denote 'coal' as a subject in a factual statement about its categorization as a resource.

• 石炭を燃焼させることでエネルギーが得られます。

  Energy can be obtained by burning coal.

  In this sentence, '石炭' is utilized within an action phrase where it acts as the direct object being burned to obtain energy.

• 石炭産業はかつて地域経済の柱でした。

  The coal industry used to be the pillar of the regional economy.

  Here, '石炭' modifies '産業' (industry), forming the compound '石炭産業' which explains the type of industry, indicating its importance in an economic context.