Final answer:
When two combining forms are present, specific spelling rules such as The Rule of Simple Addition, The Twinning or Doubling Rule, The Final (e) Deletion Rule, and Replacing Letters and the (y)-to-(i) Rule guide the correct formation of new words.
Step-by-step explanation:
When two combining forms are present in English spelling, a specific spelling rule is applied to ensure correct word formation. Notably, there are various rules such as The Rule of Simple Addition, The Twinning or Doubling Rule, The Final (e) Deletion Rule, and Replacing Letters and the (y)-to-(i) Rule. These rules guide how we combine stems with suffixes to form new words, accounting for changes that may be required.
The Rule of Simple Addition dictates that we can directly add a suffix to a base word without changing the spelling of the original word when combining forms. In contrast, The Twinning or Doubling Rule sometimes requires us to double the final consonant of a base word when adding a suffix beginning with a vowel, especially if the base word is a one-syllable word or a multi-syllable word with the stress on the final syllable.
The Final (e) Deletion Rule comes into play when a base word ends with an 'e.' This 'e' is usually dropped when adding a suffix that begins with a vowel. The (y)-to-(i) Rule suggests that when a base word ends in 'y' and the suffix begins with any letter other than 'i,' the 'y' is changed to 'i' before adding the suffix, except when the 'y' is preceded by a vowel.