The indefinite pronouns algún and ningún need to agree in gender (when possible) and in number with the noun they are substituting. Algo and alguien are not gender or number specific.

Such pronunciation overlap, particularly after sound changes deleting final vowels on words became widespread, created ...

Original: Each student will develop his or her own lesson plan. Revised: All students will develop their own lesson plans. Change point-of-view or use an indefinite pronoun. Original: A person's ...

Even Chaucer employed “they” in such a way when referring back to “whoever” (a singular indefinite pronoun traditionally replaced by “he”) in his famed Canterbury Tales. The pronouns ...