ce n'est pas acceptable, c'est inacceptable
l'acceptation is the French word for 'acceptance'
"Dessous" or "sous", either is acceptable.
les pantalons (now acceptable also as a singular, le pantalon)
"Je t'aime" means "I love you" in French. "Je t'adore" is also acceptable.
Dangereux is the most common way to say "dangerous", however risqué is also acceptable.
"ce n'est pas acceptable"
Spaghetti is an acceptable word in French.
Bouffon is an acceptable French substitute for the word "joker".
Salut! or Teins! Salut is an informal way to say hello! Teins is equivalent to hey!
French just call it ... le T-shirt. The word is commonly used and has no french synonym. It is written T-shirt or tee-shirt. Either is acceptable. The word t-shirt was not gallicized upon entering the French language, and is a masculine noun.
It is not quite as acceptable; however in ordinary speech it is fine to say it and most people won't mind.
No, the phrase Quelle heure est-ce que c'est? ("What time is it that it is?") is not acceptable French. The simpler question, Quelle heure est-il? ("What time is it?"), will be acceptable, particularly if pronounced correctly as "keh-luhr ey-teel" in French.