Learn French: Je participe aux avant-dernières réunions du pédiatre. - I participate in the pediatrician's penultimate meetings.

In compound adjectives formed by a preposition or adverb (like avant) and an adjective (like dernier), only the adjective part agrees with the noun. Since réunions is feminine plural, dernier becomes dernières, but avant never changes.

What if both parts of the hyphenated word were adjectives? Would they both agree?

Yes! If a compound adjective consists of two adjectives (like sourd-muet, meaning deaf-mute), both parts agree with the noun. Modifying a feminine plural noun, it would become sourdes-muettes. In our sentence, avant isn't an adjective, which is why it escapes this rule.

Why use aux here instead of dans les to mean "in the"?

While English says "participate in," the French verb participer requires the preposition à. When à is followed by the plural definite article les (for les réunions), they must contract into aux.

How can we tell if the pediatrician in this sentence is male or female?