The phrase "was at service" can be easily altered with a variety of antonyms, such as "was absent," "was unavailable," "was missing," or "was inactive." While "was at service" suggests that someone was present and available, the use of antonyms highlights the opposite meaning, indicating that someone was not there or unable to help. By employing antonyms, one can effectively convey the message of absence, inactivity, or lack of service. In everyday life, having a clear understanding of antonyms will help in communicating effectively, avoiding confusion and misinterpretation.