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Let's begin with the Relative Pronouns "lequel (masc. sing), laquelle (fem. sing.), lesquels (masc. plural) and lesquelle3s (fem. plural.)" They all mean "which" as the object of a preposition and are used principally for things.
C'est la porte par "laquelle" il est sorti.
That's the door through which he left.
Voici le bureau sur "lequel" j'ai laissé mes lunettes.
Here is the desk on which I left my glasses.
Now, the Interrogatives.
which? what? (adjective) = quel, quelle, quels, quelles
which? which one(s)? (pronoun) = lequel, laquelle, lesquels, lesquelles.
Lequel de ces chapeaux est le plus cher?
Which (one) of these hats is the most expensive?
NOTE: the pronoun "lequel" agrees in gender and number with the noun it replaces.
When "à" and "de" are used before the forms of "lequel", the usual contractions take place.
singular = auquel, à laquelle / duquel, de laquelle
plural = aauxquels, auxquelles / desquels, desquelles
Auquel de tes amis as-tu-écrit?
To which of your friends did you write? (OR Which of your friends did you write to?)
De quels enfants est-il fier? Desquels est-il fier?
Of which children is he proud? Of which ones is he proud?
Now, in the question: "Nous entendons beaucoup parler de projets communautaires?"
NOTE the preposition "de" because the pronoun "en" replaces "de + noun" and generally refers to things. It is usually translated into English by "some, any, of it (them), from there."
"En" is always expressed in French, even though its equivalent may not be expressed in English. "En" must be used when the noun is omitted after a number, an adverb or noun of quantity, or an idiom requiring "de."
Voici des framboises. En voulez-vous?
Here are some raspberries. Do you want some?
Elle n'en a pas acheté.
She didn't buy any. (She bought none.)
N'en parlons plus.
Let's not speak of it any more.
Vient-il de la ville? Oui, il en vient.
Does he come from the city? Yes, he does (come from there.)
The other pronoun "y" always refers to things or places and it generally replaces "à + noun" but may also replace other prepositions of position, such as "chez, dans, en, sous, or sur + noun."
Both these pronouns regularly precede the verb, except in the affirmative imperative, where they follow.