The combining form is used to create a medical term when

The word root is developed to include a vowel sound following the term to add a smoothing action to the sound of the word when applying a suffix. The result is the formation of a new term with a vowel attached (word root + vowel) called a combining form.

Explanation:

The word root is developed to include a vowel sound following the term to add a smoothing action to the sound of the word when applying a suffix.

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yes. i think it is for sure.