A French problem, the singular and plural of adjectives The plural form of principal is principaux. Under what circumstances does l become aux? Is there any rule? Can you tell me the general law of the singular to the plural of adjectives and other special laws?

A French problem, the singular and plural of adjectives The plural form of principal is principaux. Under what circumstances does l become aux? Is there any rule? Can you tell me the general law of the singular to the plural of adjectives and other special laws?

Generally speaking, it is to add - s directly at the end. If the adjective ends with - s, - Z, - x, the form will not change
But there are some special cases
Adjectives ending with - Au, - EU, - Eau, plural with - x;
Adjectives ending with - Al should be - aux in plural;