Final answer:
The question focuses on English spelling rules related to ending bases with an [s] sound, twinning when a consonant doubles after a short stressed vowel, and simple addition, where doubling occurs due to suffixes or prefixes.
Step-by-step explanation:
The question is about the rules of spelling in the English language, specifically focusing on the spelling of words that have bases ending in an [s] sound. In these cases, the sound is influenced by the preceding vowel and whether it is stressed and short. This will dictate how the final [s] is spelled. Additionally, the question explores the concept of twinning, where a consonant is doubled after a short vowel in some cases, and situations of simple addition, where the doubling occurs for other reasons.
For the twinning rule, twinning occurs when a short, stressed vowel is followed by a consonant; the consonant is doubled. In cases of simple addition, the double letters can result from the concatenation of a prefix or suffix that starts with the same consonant as the base word ends. Understanding these spelling conventions helps explain how some words achieve their correct orthography.
Examples of words with twinning might include rubbing (rub + -ing) or sitting (sit + -ing). Examples of words where the double letters come from simple addition might include ebb (e- + bb) or webbed (web + -ed).