"De doesn't always have an article after. When "de" is the transation of "of", it's only "de". Ex : jambe de bois = wooden leg / leg made OF wood. "de la" = "some". Ex : veux-tu de la mayonaise (do you want some mayo?)

2°) in french, we use "du" which is a contraction on "de le" 1°) hard to answer the first question. For me, it just "sounds" better... But I found an article about this problem on the WordRef forum: http://forum.wordreference.com/showthread.php?t=13968 Maybe someone will provide a better explanation. sorry!

1 Paris est la plus grande ville de France. (why not de la) => there is an exception for every name of city, country and continent. "de" for a feminine name of a city/country/ continent - La France : Paris est la plus grande ville de France "du" for a masculine name of a city/country/ continent - Le Brésil : Sao Polo est la plus grande ville du Brésil and "d' " for name of a city/country/ continent that starts with a voyel - Alger est la plus grande ville d'Algérie 2 Le Pacifique est le plus grande ocean du monde. Whenever you want to write "de + le" in french, we contract it as "du" There is other contractions : - de + le = du - de+ les = des - à + le = au - à + les = aux