It is indispensable to master a language to communicate ?
Every country has its own language and it can be a problem for stangers to communicate or to be understood. But there are always solutions.

If the two persons make an effort , it’s always possible to communicate . for exemple , last years, I went to germany but I don’t speak Germain, and with the hands or with pictures it can be easier.
Maybe that it’s possible to meet someone who can help us , when he speaks both languages . There are always persons who are bilingual.
For exemple in the text, spiro likes helping English people because he lived in America, Even if the family does not speak it Greek, it manages to communicate thanks to other person.
However, the various examples show that it is possible to find solutions, thanks to various means, but that shows us that for really communicating, (if one is only opposite a person) to control languages is essential.
In the text for example, the family does not speak it Greek, and does not understand what the taxi drivers want. I remember that when I was in New York during my last holidays, at the moment of the loading to the airport, it is essential to understand and of speaking English, without what the discussion is impossible and the fact of being misunderstood is obligatorily problems. It seems obvious that to travel, to move easily without dependent problem of the voyages, it is necessary to have a “minimum” of vocabulary (it is necessary to be able to ask to nourish, to place, find a direction…)
If one is opposite a person not understanding our language, the discussion will remain very basic but there will not be a “true exchange” it will not be a true communication with ideas, the possibility of arguing…. So it is difficult to answer yes or not at this question, because one cannot really say that it is essential to have a command of a language to communicate but it is obviously easier. That depend too direction `to control', because it