Final answer:
The suffix -ed is used in English to denote the past tense of a verb, indicating a completed action. The pronunciation of this suffix varies, and certain historical verb forms do deviate from the modern -ed construction. Spelling changes can occur based on specific rules when adding suffixes.
Step-by-step explanation:
In English language studies, the suffix -ed is commonly used to form the past tense of regular verbs, indicating an action that has been completed in the past. This suffix can be pronounced in different ways—[d], [id], or [t]—depending on the verb it is attached to. For example, the verb 'look' in the past tense is 'looked,' where the -ed suffix sounds like [t].
Some verbs have historical roots that affect their past tense form. Verbs like 'feel' change to 'felt' in the past tense, demonstrating older forms of English where a suffix that sounded like [t] was sometimes even spelled with a . In modern English, this is not common and the past tense for most verbs is formed by adding -ed.
When adding a suffix to a verb or another word, the spelling of the base word can change depending on a set of rules. For instance, when adding a suffix that starts with e, i, or y to a word ending in a soft , the remains unchanged to maintain its soft sound.