How do you know when to use which preposition?
depende DE for example..."depend on"...i would think it's "en".
3 Answers
I'm going to go with Helado on this one. Just learn them on a case-by-case basis. Every language (be it Hindi, Gujarati, Spanish, French, etc.) is going to have a different (and completely arbitrary) way of using pronouns.
I'd recommend learning a verb with at least one of its prepositions. Remember that some verbs may have more (like in English we have "cheat on" and "cheat against") and some have none ("querer" takes no prepositions when it means "to want"). Often a change in preposition changes the meaning of the verb so I consider prepositions a part of the verb.
Essentially, always learn your verbs in a way where you'll be able to see how it relates to the rest of a sentence. Never just learn the verb as one word. Learn it with it's prepositions. Learn if it acts like "gustar" and "encantar".
Also remember that the prepositions won't always line up with English. English may use no prepositions when Spanish uses one ("luchar" takes "contra" or "con" when "to fight" takes none). And something English uses prepositions and Spanish uses none.
Just remember to look at the verbs in context (i.e. with example sentences) if you're ever unsure of a verb's preposition. The Spanish Dict dictionary gives several excellent ones.
I could then perfectly revert the question and ask you. How do you know when to use and which preposition, in English.
Would that be fair enough?
I have two possible layman theories:
1) That's just the way Spanish works. Kind of like 'jugar a' which literally translates to 'play at'.
2) depender originates from the Latin d?pendere, meaning 'to hang down'. I guess depender de would be along the lines of 'hang down from'.
Hopefully, someone else will be able to provide a much more informative answer (which I will also wait for).