Final answer:
Yes, a combining vowel is typically required between two word roots. However, there are exceptions to this rule.
Step-by-step explanation:
Yes, a combining vowel is typically required between two word roots. However, there are some exceptions to this rule. If a word root ends in a consonant-vowel-consonant (CVC) pattern and is followed by a suffix that starts with a vowel, the final consonant is usually doubled before adding the suffix. This doubling is done to maintain the correct pronunciation of the word.
For example, if we add the suffix -ing to the word 'hop,' we double the final consonant 'p' to get 'hopping.'
However, there are instances where a combining vowel is not required. This occurs when the word root ends in a CVC pattern and has strong stress on the final vowel before and after adding the suffix, or when the consonants 'w' and 'y' function as vowels in certain circumstances. In these cases, the final consonant is not doubled.