The document discusses the structure and usage of conditional sentences in English, emphasizing the role of adverbial clauses (if-clauses) and main clauses (then-clauses). It outlines different types of conditionals: present real, hypothetical, and impossible past situations, along with their grammatical forms and examples. The author, María Irene Albers de Urriola M., is a PhD candidate specializing in applied linguistics and computer technology in education at the University of Sevilla.