Final answer:
The words hydrant, hydroplane, hydrology, and hydrotropic share the common root word 'hydro-' related to water.
Explanation:
The words hydrant, hydroplane, hydrology, and hydrotropic have a common root word: hydro-, which pertains to water.
In these words, hydro- serves as the base that gives the core meaning related to water. This root hydro- can be seen as a free morpheme as it can stand alone and maintain its meaning.
For example, in hydrant, hydroplane, hydrology, and hydrotropic, hydro- is the common base that links them together.
Learn more about morphology and root words here:
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