What is the difference between using "de" and "que" for the English word "to"?
Here are two examples where `de` and `que` are meant to translate to `to` in English: `Donde tengo que dejar los documentos?` = Where do I have to leave the documents? `Es imposible de saber` = It is impossible to know. Both `que` and `de` mean `to` in these sentences. My question is what is the difference such that one must be used over the other?