How many languages can a person know? At least as many people as you know. If you are observant and flexible in your perception, you will be able to understand the language of everyone who meets you, and become understandable to him, without deviating from your language. This is the opinion of one of the authors of this book, a philologist, translator, creator of a unique psycholinguistic methodology for accelerated teaching of foreign languages ​ ​ Dmitry Petrov.