French language Q&A Forum

What do the preposition à and de Mean Un the Following sentences ?

Je parle à mon copain

Vous devriez ajoute 'moudre' a la liste des verbes irregulier

I am trying why the woman's male partner addresses her as "tu" in one sentence, then as "vous" in the next sentence. Would please explain why?

I found this clip on You Tube very useful to help clarify my understanding, and you may like it too! Object Pronouns with Madame Curnow - Part 2 (Sorry, this is not a question)

Comme chaque année depuis que tu nous as quittéS

I did read the lesson on past participle agreement with avoir but am still not sure why the 's' is needed in the above.

position of prochain relative to nouns

I do not understand why "Sams does Aikido" is translated as "Sam fait de l'aïkido.".  The lesson says that in front of masculine nouns that de le and les will contract to du and des.  Why is this not "Sam fait du aïkido"?  

Thank you.

Surely the suggested (in the final translation) is lacking in the latter part of the sentence. Shouldn't there be "quelque chose que vous aimez" added? How is this inferred?