Slacks (meaning casual trousers) is plural. It has no singular form
Trousers are "les pantalons" (used to be plural, but is widely accepted nowadays as a singular object : 'je vais mettre mon pantalon').
Tu as is singular is French. The plural French form is Vous êtes.
Hors d'oeuvres is the English plural, hors d'oeuvre is the English singular. Hors d'œuvre is the French plural and the French singular.
The singular form is a pair of trousers; the plural form is pairs of trousers.The noun trousers is one of a group of words that are a short form for 'a pair of', words for things things that require two halves to make one.Some other nouns that are used in their shortened form are pants, shorts, glasses, binoculars, tweezers, tongs, or pajamas. The singular forms are a pair of, the plural form is pairs of.
It is plural and French.
The noun 'trousers' an uncountable noun, a form of binary noun, a word for something with two parts making up the whole; a shortened form for 'a pair of'.The singular form is a pair of trousers.The plural form is pairs of trousers.
"Vous avez" is conjugated in the second person plural form in French. It is used to address more than one person in a formal or polite way.
Une chaussette is a feminine noun in French.
Cinéma is the singular form of a masculine noun in French. The plural form is cinémas and may be translated as "films," "movie theaters" or "movies" in English. The pronunciation will be the same for the singular and the plural forms in French: "see-ney-ma."
If by pants you mean trousers then the word is un pantalon curiously the word is singular in french.
"Bloc-notes" is singular. The plural would be "blocs-notes".