Which suffix indicates the past tense of a verb?

• A. It marks a completed action
• B. It indicates future tense
• C. It denotes plurality
• D. It indicates the past tense of a verb

Answer: (D)

Understanding how suffixes show when an action happened is key. A suffix that marks past tense signals that the action occurred in the past, often indicating it’s completed. This is precisely what the description says: the suffix indicates the past tense of a verb. For example, adding -ed to walk to form walked places the action in the past. The other ideas describe related concepts but don’t name the function itself—future tense is about what will happen, plurality is about number, and while a completed action fits with past tense, naming the past-tense function directly communicates the role of the suffix.