When you leave the article out: 1. In negative statements. Ex. Je n'ai pas de pain. I don't have bread. Elle n'a pas de vin. She doesn't have wine.
When the definite article is used with an adjective. Ex. Il a de bons amis. "He has some good friends.
After the preposition DE in an adjective phrase. Ex. J'aime mon livre de français.
This information is from a French grammar book. The book shows that's when NOT to use the definite article with DE
There are a couple of problems with that. First, it is "garçons" (plural), and secondly where an adjective goes in relation to the noun it is modifying in French depends on the type of adjective it is. A handy mnemonic for knowing if an adjective goes before the noun is BAGS (Beauty, Age, Goodness, Size). If the adjective relates to any of these categories, than it goes before the noun. "Bon/Bonne" (masculine/feminine forms) falls under "Goodness", so it goes before "pain".
Yes. There's a much better explanation than mine here http://french.about.com/od/grammar/a/de-vs-du-de-la-des_2.htm
Yep, what potato_jam said. There's also a comment from a user, Sitesurf, somewhere that explains this, too.
The explanation in this thread should help us have better grasp of the difference and when to use what: http://forum.wordreference.com/showthread.php?t=13411
"mangent" and "mange" are pronounced the same way.
The present participle "mangeant" would be pronounced "man-gent". http://french.about.com/od/grammar/a/presentparticiple.htm
When listening to French, the definite articles (le/la/l'/les) are the giveaways for if the noun is in singular or plural: Le garçon (boy [singular]); Les garçons (boys [plural]). Le sounds like uh as in tug, and Les sounds like lay.
But wait, there's more...
Les: Although "Les" sounds like "lay" in front of a plural noun with a consonant at the beginning. For instance, Les garçons.
Let's turn it up a notch: Les will sound like leh as in let in front of a plural noun beginning with a vowel, or h, OR adjective beginning with a vowel or h; the "s" from "les" will carry it's sound onto the next word (the adjective, or the noun beginning with a vowel or h), and the "s" will sound like a "z" as in zulu.
Les livres (les sounds like lay)
Les hommes (les sounds like leh zommes)
Les anciennes écoles (les again, will sound like leh zanciennes écoles)
Remember, the s (and most consonants in French) at the end of words don't get sounded out ;)
One last thought: (so worth it) There is a concept called homophones (words that sound the same, but have different meanings...Take heed to this example: The difference between "water" and "zoo" in french.
water: singular: l'eau (sounds like lo as in low)
water: plural: les eaux (sounds like leh zoh)
zoo: singular: le zoo (sounds like luh zoh <- will sound confusing, like "les eaux")
zoo: plural: les zoo (sounds like lay zoh)
I think I was on the animal section when I was given just the french audio "...zoh", and I got it totally wrong. Whenever you learn a new word, play with it like this, and find out if there is another word that may sound like it. Will save you from embarrassing moments when speaking french.
First, read DrRichthofen's rather detailed explanation above. Second, realize that you can learn to tell the difference by listening closely. Les garçons sounds quite different than le garçon. The sound of the article gives it away completely. Type these two phrases into Google Translate and click the speaker button to hear the words pronounced. Repeat until you can clearly distinguish the sounds. It is really not difficult. Once you have learned to distinguish between le, la, and les, you will have the clue you need to know that it is "mangent" and not "mange" (even though those two words do sound exactly the same). As you progress, you will look back at this and realize how simple it really was.
les is used for the plural e.g. les garcons = the boys, yet le is only used for the singular e.g. le garcon= the boy. literally just remember if your using les there are more than one of what you are describing and you have to add an s onto the following words e.g. les pommes sont rouges = the apples are red instead of le pomme est rouge = the apple is red. see no s's :D
I Dont know whether that was helpful but i hope it helps.
Try to listen closely. Le sounds like LOO and Les sounds like LAY. It can be hard to hear at first but if you really try to hear it and try to be aware of it eventually it will be a little more obvious when you hear it. We have to train our minds to hear a new language sometimes.