Sorry, but this is nonsense. Fluency in a natural language is a woolly concept. There is no such thing as being "completely fluent." There are various dimensio

Sorry, but this is nonsense. Fluency in a natural language is a woolly concept. There is no such thing as being "completely fluent." There are various dimensions of language proficiency and even native speakers vary greatly in their abilities. Even the most eloquent writers and speakers of a natural language are ignorant of vast portions of it, after using it for decades.