You're right, they're antonyms. Using just synonyms makes it too simple, so the rules are: a synonym, an opposite, or an association. So for "before," it can be, for example: ahead, back, after, behind, etc. This creates more variety, but there is still only one answer in the end.
destination + before = a time word
had "thereafter" as solution. I'm not sure how that should work. How is "after" related to "before" other than the negative?
You're right, they're antonyms. Using just synonyms makes it too simple, so the rules are: a synonym, an opposite, or an association. So for "before," it can be, for example: ahead, back, after, behind, etc. This creates more variety, but there is still only one answer in the end.
I see. I just didn't read the instructions :)