De vs Du, De la, Des:Lesson on French prepositions and articles

The preposition de tends to be very difficult for French students, even at advanced levels. Trying to figure out whether to use de, du, de la, or des can be a real challenge! This lesson is a summary of when to use the preposition de all by itself and when to use the indefinite article, partitive article, or de + definite article (which looks like the partitive - but isn't. Ugh!)

Note: This lesson assumes that you already understand the key grammar topics discussed. If necessary, you can review them by clicking on the hyperlinks.

A.	Partitive and Indefinite article
	1.	The partitive article indicates an unknown quantity of something, usually food or drink
		Nous voudrions du lait.		We'd like some milk.
		J'ai mangé de la glace.		I ate some ice cream.

	2.	The plural partitive article des refers to something plural uncountable.
		Il a mangé des épinards.		He ate some spinach.
		Peux-tu me donner des conseils ?		Could you give me some advice?

	3.	The plural indefinite article des refers to more than one countable thing in an indefinite sense.
		Il a des livres intéressants.		He has some interesting books.
		J'ai acheté des chaussettes.		I bought some socks.

	4.	In a negative construction, the partitive and indefinite articles (singular *and* plural) change to de, usually meaning (not) any:
		Nous ne voudrions pas de lait.		We don't want any milk.
		Je n'ai pas mangé de soupe.		I didn't eat any soup.
		Il n'a pas de livres intéressants.		He doesn't have any interesting books.
		Je n'ai pas acheté de chaussettes.		I didn't buy any socks.
		Nous n'avons pas de voiture.		We don't have a car.
		a.	Except if the verb is être:
			C'est une poire, ce n'est pas une pomme.	It's a pear, it's not an apple.
			C'est de la viande. - Ce n'est pas de la viande.	It's meat. - It's not meat.
		b.	Or if you want to stress the negative aspect:
			Je n'ai pas de sous - Je n'ai pas un sou.	I don't have any money - I don't have a (single) cent.

	5.	When the plural indefinite or partitive article is used with an adjective that precedes a noun, des changes to de.
		J'ai des amis. - J'ai de jeunes amis. (Note: J'ai un jeune ami)		I have some friends. - I have some young friends. (Note: I have a young friend)
		J'ai mangé des épinards. - J'ai mangé de bons épinards. (Note: J'ai mangé de la bonne sauce des épinards)		I ate some spinach. - I ate some good spinach. (Note: I ate some good spinach sauce)

B.	Adverbs of quantity and Adjectives
	1.	After most adverbs of quantity, de stands alone. (see lesson for exceptions)
		Il y a beaucoup de problèmes.		There are a lot of problems.
		Peu d'étudiants sont ici.		Few students are here.
		J'ai mangé moins de soupe que Lucie.		I ate less soup than Lucie.

	2.	After adjectives, de stands alone.
		La chambre est pleine de vêtements.		The bedroom is full of clothes (clothes in general).
		Les tables sont couvertes de gâteaux.		The tables are covered in cakes (a bunch of cakes).

	3.	Except if the noun after de refers to specific people or things - then de is used with the definite article.
		Beaucoup *des problèmes* sont graves.		A lot *of the problems* are serious (specific or previously-mentioned problems).
		Peu *des étudiants de Thierry* sont ici.		Few *of Thierry's students* are here (not students in general).
		Le repas que Lucie a préparé est délicieux, mais j'ai mangé moins *de la soupe* que toi.		The meal that Lucie made is delicious, but I ate less *of the soup* than you (soup from previously-mentioned meal).
		La chambre est pleine *des vêtements de David*.		The bedroom is full *of David's clothes* (specific).
		Les tables sont couvertes *des gâteaux dont je t'ai parlé*.		The tables are covered in *the cakes that I told you about*.

C.	Descriptive vs Possessive de
	1.	To describe a noun with the de + descriptive noun construction, use de.
		le livre d'étudiant		student book (book for or about students)
		le panier de chien		dog basket (basket for a dog)

	2.	To show possession of a noun, use de + definite article*
		le livre de l'etudiant / le livre des étudiants		the student's / students' book (belongs to the student/s)
		le panier du chien		the dog's basket (as opposed to Lisa's basket)
		* Of course, a proper noun would not need a definite article
		le livre de Michel		Michel's book

	3.	If the descriptive noun is modified in order to distinguish a certain group of the given noun, use de + definite article. Note that these can then appear either descriptive or possessive. This construction is often used in advertising.
		le livre de l'étudiant étranger		the foreign student book (book for foreign students) or the foreign student's book (belongs to the student from Botswana).
		le panier du chien délicat		the discriminating dog's basket ("for discriminating dogs" or "there are two dogs; this basket belongs to the discriminating one").

D.	Verbs with prepositions
	When verbs and expressions must be followed by the preposition de, the de vs des issue is similar to part C, above.
	1.	If de simply introduces a noun, use de.
		Il faut changer de train ici		You have to change trains here
		Nous avons besoin d'argent		We need money

	2.	If the noun that follows de is modified, use de + definite article
		Nous voulons profiter du nouvel accord		We want to take advantage of the new agreement
		Il s'agit de la réforme agraire		It's a question of land reform