"Dankon, ĝis la revido!"
Translation:Thank you, see you later!
Yeah I think you are right.... maybe they can add this option... I think you can retry the question and wirte the same answer again, you will then notice there's a way, on the feedback screen, to suggest another possible translation... that way the developer team can take it into consideration faster...
In esperanto, words are made of one or more roots and endings. Verbs, adjectives and nouns always have endings. Most of adverbs have endings too. The primitive adverbs and the other gramatical classes don't have endings.
viro has a root (vir) and a noun ending (o).
malbela has two roots (mal and bel) and an adjective ending (a).
saluton has a root (salut) and two endings, a noun ending and an accusative ending (o and n).
ĝis has only a root (ĝis) and no ending, because it is a preposition.
All adpositions in esperanto are prepositions, so they have to come before the noun phrase. http://en.wikipedia.org/wiki/Esperanto_grammar#Prepositions
There are some words which Zamenhof left without grammatical endings for (what I will say here to keep it short) no real reason, BUT you can still put those endings on if you want. So you can in fact say "ĝise" or "ĝiso" or whatever else you need according to situation, for example. It's just that a lot of people don't do it because they weren't specifically taught that it's okay, and so they don't even think about it.
It's because of what the literal translation is, which is "until the re-seeing". In that literal translation, the "la" makes sense. When we read it as "see you later" in English, we read the implied meaning rather than the literal one, which is why in languages in general, translations aren't always a 1:1 correlation.