"I am lying beside the window."

Translation: Az ablak mellett fekszem.

[_paranoia_]

Ok, so this one rather annoyed me. It seems to me that many of the sentences in this section could be translated using the -nál/nél construction, or with another construction such as mellett. Indeed, I think that "by" translates better with mellett, although in reverse it's true that "-nál" sometimes translates best as "by".

Why doesn't this one accept "mellett" or "-nál"?

[vvsey]

It should be accepted. There is some difference between "-nál" and "mellett", especially in some other situations, but English is more liberal here. So, both solutions should be reported, and accepted.

[GerSzej]

why fekszem ? it seems that it is the definite conjugation

[mizinamo]

fekszik is an -ik verb; those have -m in the indefinite conjugation for én (which looks like the normal definite ending, yes).

[GerSzej]

ah yes! Thank you

[androghost]

Could "Mellet az ablak fekszem" by right?

[mizinamo]

No, for the same reason that "I am lying the window beside" does not work in English.

"beside" is a PREposition, which means that it stands BEFORE its noun: "beside the window" (first "beside", then "the window").

mellett is a POSTposition, which means that it stands AFTER its noun: az ablak mellett (first az ablak, then mellett).

English has one common postposition: "ago". We say "I moved here three years ago." But we can't say "I moved here ago three years" -- that's like saying mellett az ablak.

[carolgoslen]

How do I know when to use -nal/nel and when to choose mellett?

[joemagyarul]

You can check this discussion out and see if it helps: https://www.duolingo.com/comment/22142630/Difference-between-adessive-case-and-mellett