À or de?
All over these months I’ve been using Duolingo, that pair got me confused the most. And thanks to the crown system, I think I’ve distinguished the two and could differentiate them.
À is used for Destination or Location. The à usually comes directly before the place mentioned.
J’habite à Manille (I live in Manila)
Je vais à Espagne (I am going to Spain)
Nous allons à Nantes (We are going to Nantes)
De, on the other hand, signifies the origin
Je pars de Nantes (I am leaving from Nantes)
Je viens d’Île-de-France (I come from Île-de-France)
By means of distance à is placed before the distance, while de indicates the starting point.
Elle habite à cinq kilomètes de chez moi (She lives five kilometres from my house.)
C’est à une heure d’ ici (It is an hour from here.)
À determines the purpose or onto what use the thing is for. Sometimes the syntax « noun à smth » is used. Wherein the "smth" signifies the use of the “noun”.
Une tasse à thé (Lit:cup for tea, Trans: teacup)
In the example above, the noun « tasse » was accompanied by « thé », therefore stating that the cup was for a tea, or the cup was intended or to be used for a tea. Therefore, it’s teacup.
Carte à jouer (Lit: card for play, Trans: playing card)
The « carte » was intended for « jouer » (play), same analogy.
Cuiseur à riz (Lit:cooker for rice, Trans: rice cooker)
And those examples to be compared using de. The use de implies the description or the contents of a certain object.
Une tasse de thé (cup of tea)
This examples implies that there is a cup, and it is full of tea. We don’t care what type of cup is that specifically but the point is that, there is a cup and it is filled with tea. Its content is tea.
Cuiseur de riz (cooker of rice)
This is not specifically a rice cooker, the machine itself. But this could imply for a human subject. In rural areas, some families assign chores to different members of the family. Such as, the brother is going to cook the rice. And if a person is to cook rice, then, he has to do it manually, he has to light a fire, etc. (I found this term weird, but I know you know this is true to real life.)
Regarding possesives, À has three syntaxes:
- c’est à + sp/noun/name.
- noun + être à + sp/noun/name.
- c’est + noun + à + sp.
(sp means stressed pronoun, the lui, elle, moi, toi, thingys)
C’est à lui (It’s his.)
Cet enfant est à toi. (This is your child)
C’est une amie à moi. (She’s a friend of mine.)
Keep in mind that à is used after être, exception to 
However, there is an exception to the use of syntax 3. For syntax 3 only allows the use of sp, and not noun/name. Thus if these are used, then de should be used.
C’est un verre du chef. (Not c’est un verre au chef) (or au chef? Lols)
Moreover, de is used after « c’est + noun », if a name/noun is intended. Also, it is used for noun adjuncts.
Par exemple: l’album de photo (photo album)
Sorry if I won’t mind explaining further, but here’s a diagram for it.
Also, I’m sleepy when I was typing this thing, so if there’s any discrepancy, tell me down in the comments below. And also I’m gonna ask, should I continue discussing this thing furthermore in more aspects? Like on impersonal expressions or should you place à or de before some infinitives?