I have often heard that you can use je when doubting which preposition to use. Is this always the case?
Je is not intended for occasions of doubt, but rather when a preposition is needed but none of the defined prepositions are suitable. In practice, je is used infrequently, and most often in set phrases.
- Time espressions (je la tria horo)
- je via sano
- je la barbo de Zamenhof!
- plena je io (although plena de io is more common.)
- graveda je knabo
- mi kredas je Dio