The French preposition à is generally summarized as "to, at, or in," but it has quite a few more meanings and uses than that.
As if the myriad possible translations of à and de aren't enough, these two French prepositions also have complementary and contrasting uses.
One of the eight parts of speech, adjectives are a type of modifier. They serve the same purpose in French and English, but they are very different in two respects.
There are six French adjective / pronoun pairs, where an adjective + noun can be replaced by a corresponding pronoun.
When describing someone as capable of doing or determined to do something, a preposition is required between the adjective and verb. In French, the choice of preposition depends on the adjective that precedes it, not the verb that follows.
As you might guess from their name, adverbial pronouns are caught between two worlds: they are pronouns in the sense that they replace nouns, and at the same time they are adverbs representing a place, a quantity, or the object of a proposition. French has two adverbial pronouns: en and y.
Adverbs are descriptors: they can modify several different parts of speech, including themselves. Virtually every French word that ends in -ment is an adverb, equivalent to -ly in English.
Adverbs of frequency express how often the action of a verb occurs.
Adverbs of manner express how the action of a verb occurs. In English, the vast majority of adverbs of manner end in -ly, whereas in French, they mostly end in -ment. They are created from adjectives.
Adverbs of place express where the action of a verb occurs.
Adverbs of quantity express how much, how many, or to what extent.
Adverbs of time express when the action of a verb occurs.
Most French verbs are conjugated with avoir as their auxiliary verb in compound tenses and moods, and therefore do not require agreement with their subjects. But avoir verbs do need agreement in a very specific construction: the past participle must agree with the direct object when it precedes the verb.
All pronominal verbs are être verbs in compound tenses and moods like the passé composé, which means that the past participles must agree with their subjects - at least in theory. In fact, it's not quite so straightforward.
The three French verb constructions which include some form of être plus a past participle usually require grammatical agreement of the past participle with the subject.