"Il sert de frontière" probably relates to a masculine, geographical element like "un fleuve" (river) or "un glacier", "un canal" (channel), "un pont" (bridge) which is used as (serves as, constitutes, stands for, marks... ?) the border (boundary), between two countries/regions.
Quote: "The witness and his family nevertheless managed to cross the bridge that served as the border and went to Bujumbura"
i see that it is not needed obviously, but i wanted to know why. or at least what cases one should not use articles after the preposition. for example, when you use a negative sentence such as "il n'y a pas de pain". you shouldn't use "du" in this case, and i understand why. i'd like some sort of explanation like this, if there's any.
Sorry! I'll keep looking for a better explanation, but start here at "VI. Means/Manner": http://french.about.com/od/grammar/a/preposition_de.htm
Message from Sitesurf:
Cases where the article is dropped after "de" 1. With specific verbs constructed with de, and followed by an unmodified noun, the article is dropped: - avoir besoin de / avoir envie de / changer de (train, chemise, etc.) / manquer de / s'occuper de / se passer de / servir de (to put to use as) / vivre de / se tromper de... 2. Content or description (complément de nom): un mur de pierre, une tasse de thé, une chanson d'amour, salle de classe, jus d'orange... 3. With adverbial expressions about quantity: peu de, moins de, plus de (more), beaucoup de, autant de... 4. All negative expressions: plus de (no more), pas de, jamais de...
No, neither of the expressions using "he" is correct, nor the use of "one". Someone had the idea that it would simplify things if "a" was universally interpreted as "one". In fact, much of the time it is very awkward (despite being grammatically correct) to use "one". To make it worse, the computer now thinks that one can insert "1" for "one" anytime and we occasionally see this in answers being displayed. It's utterly ridiculous but we're stuck with it until the problem is fixed.
i heard various things over and over: Il sert de St. Pierre. Il sert de pierre....and none of that was close. I hope this is not a problem with my hearing. I hope to take a tablet to all conversations so folks can write me what they are saying. I fear I will never get it. I thought someone was going to eat St. Peter.
I get your point that "border" is the word used by English speakers and you will see that reflected in the "best answer". Sometimes non-native English speakers assume that it must be translated as "frontier" (which is also correct) because it just looks that way. While it may be understood, it is not natural (idiomatic) English.
"Il sert de" means "it is used as" or "it serves as". So the pronoun "he" and the preposition "at" are wrong.
In this story, "il/it" is a thing, like a wall or river, which separates two countries.
If the sentence were "he serves at the border" (his job is located at the frontier) the French sentence would be "il sert à la frontière".