The book "Ecos da mudança na marcação do Parâmetro do Sujeito Nulo no PB" by Juliana Marins offers an in-depth analysis of the changes in Brazilian Portuguese (PB) regarding the marking of the null subject parameter. It particularly examines existential sentences with the verbs "haver" and "ter," comparing these structures with European Portuguese (PE). The author illustrates how the use of "ter" instead of "haver" in certain sentence constructions relates to PB's ability to identify an empty category in the subject area. Furthermore, the emergence of new sentence structures in PB, which are considered ungrammatical in PE, is discussed. These changes are viewed in the context of syntactic agreement, which does not occur in PE.