The four cases in which the partitive article gets "reduced" (i.e., from its full form to a simple "de"): after a negative adverb, after a quantitative expression, with a preceding plural adjective, and in compléments prépositionnels.
The negative particles other than pas/point: plus, jamais, guère, personne, rien, ni…ni, aucun, ne…que.
Ins and outs of the French construction "ne…que," or "the 'que' that excludes from negation.
Ne used without pas, both 1) having negative force, and 2) not having negative force.
Examples of the conditionnel concessif from Chloderlos de Laclos's famous epistolary novel of 1782. Some involve the conditional present introduced by quand (rather than the imperfect indicative introduced by si), and some involve the imperfect subjunctive.