"A pig is drinking milk."
Translation:Un cochon boit du lait.
I wrote that some time ago about water (eau) but it is valid for milk:
o "boire l'eau" : drink the water. Same meaning as in English, ie, not water in general, but the water that is identified (the one on the table for ex.). Since "eau" (feminine noun) starts with a vowel, you have to "elide" the definite article and use an apostrophe, to ease the pronounciation (LO instead of LA-O). o "boire de l'eau" is the way to mean "drink (some) water", ie a certain quantity of water. The construction is "de + definite article". Note that, again, the article was elided (de l' =de la). o "boire d'eau" is only used in negative sentences: "je ne veux pas boire d'eau". Here, for the same reason as before "de" is elided, and the meaning is the same as above (unspecific water).