DE "de la + nom féminin" = Il vient de la campagne. "de l' + nom masculin ou féminin" = Il vient de l'école. "de + le"doesn't exist,so you use "du + nom masculin" : Il revient du travail. "de + les" doesn't exist,so you use "des + nom pluriel": Il vient des Etats Unis. It is quite difficult to really understand the diffference and be good at that ! If you really want to understand everything use that link : http://french.about.com/od/grammar/a/de-vs-du-de-la-des.htm and do the exercice for being sure that you understand everything. This is some sentence with the coffe for help you to understand Je vais acheter du café (coffee that you drink) Je suis allé dans un café (coffee shop) et j'ai bu beaucoup de café (coffee that you drink) Il n'y a plus de café (coffee that you drink) Qui veut du café ? (coffee that you drink) I hope it helps you

Another note that might help, in addition to what Aloïse wrote: if you're asking about the number (countable) of a thing, you need to use the plural, so you would write "Combien de genres." The singular is for when you are asking about a non-countable quantity, as in: "Combien d'acide sulfurique faut-il boire par jour ?" "Combien d'or avez-vous donné aux extraterrestres qui ont atterri dans votre jardin ?" A coffee shop is "un café." To make it a complete sentence, you could use the "y a-t-il" construction: "Combien de genres de café y a-t-il au café ?" = How many types of coffee *are there* at the coffee shop? I'll leave it to an expert to tell you whether the best word to use here is "genre," "variété," "préparation," or something else. And how to make that sentence less repetitive. :-)