The words that contain an affix in the given options are:
1. ☐ unhappy
2. ☐ inchworm
3. ☐ reread
4. ☐ comfortable
Explanation:
1. **Unhappy**: The affix "un-" is added to the word "happy" to change its meaning to the opposite, forming the word "unhappy."
2. **Inchworm**: The word "inchworm" does not contain an affix.
3. **Reread**: The affix "re-" is added to the word "read" to indicate doing something again, resulting in the word "reread."
4. **Comfortable**: The affix "-able" is added to the word "comfort" to form the adjective "comfortable," indicating the ability to be comforted.
