-ger verbs are regular -er verbs that are also stem changing. The most common -ger verb is manger.
For manger and all other regular -ger verbs, the stem change is the addition of an e after the g. This only applies in the nous form. In this case, the change is made to preserve the soft g pronunciation rather than the hard g that would be present if the e were not included.
The partitive article de indicates, among other things, the word some. As learned earlier, de and le contract (combine) into du, as de and les contract into des. Also, instead of du or de la, de l' is used in front of vowels.
When speaking about food, the partitive article is used at some times while the definite article (le, la, les) is used at other times, and the indefinite article (un, une) in yet another set of situations. In general de refers to a part of food (a piece of pie) whereas the definite article (le) refers to a food in general (I like pie (in general)). The indefinite article refers to an entire unit of a food (I would like a (whole) pie).
When speaking about preferences, use the definite article:
J'aime la glace.
I like ice cream.
Nous préférons le steak.
We prefer steak.
Vous aimez les frites.
You like French fries.
When speaking about eating or drinking an item, there are specific situations for the use of each article.
Definite article (specific/whole items)
J'ai mangé la tarte.
I ate the (whole) pie.
Indefinite article (known quantity)
J'ai mangé une tarte.
I ate a pie.
Partitive article (unknown quantity)
J'ai mangé de la tarte.
I ate some pie.
In the negative construction, certain rules apply. Un or une changes to de in a negative construction, meaning, in this context, any. Similarly, du, de la, or des change to de in negative constructions.
To say some of it without specifying the exact object, the pronoun en can be used. Additionally, en can mean of it when it is not specified. For instance, instead of saying J'ai besoin d'argent, if the idea of money has already been raised, it can be stated as J'en ai besoin. This is because en replaces du, de la or des when the noun is not specifically mentioned in the sentence.
Like with me, te and other pronouns, en (meaning some) comes before the verb.
Tu joues du piano? Non, je n'en joue pas.
Do you play piano? No, I don't play it.
Vous prenez du poisson? Oui, j'en prends.
Are you having fish? Yes, I'm having some.
Vous avez commandé de l'eau? Oui, nous en avons commandé.