"主神朱庇特的" can be translated as "of the supreme god Jupiter" or more contextually fitting expressions like "pertaining to Jupiter, the king of gods" depending on the specific sentence structure.
For example:
The power of the supreme god Jupiter (主神朱庇特的力量)
The myths pertaining to Jupiter, the king of gods (与主神朱庇特相关的神话)
If it's part of a title or phrase, it might be translated more directly as "Jupiter's" (朱庇特的), like "Jupiter's thunderbolt" (朱庇特的闪电).
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