I know times have changed, but we were always taught that 'can' was a 'non' word, unless talking about a (tin) can, and we were never allowed to say 'can I' or 'can you', but 'may I' or 'will or would you'. But in this case, is it a correct exchange for 'Do you see the boy'? and could it be used in any similar phrase?
The reason you were 'not allowed' to use 'can', was not because it is a 'non' word. It is a proper word and does actually have a proper use.
You were likely told not to use 'can' in situatuons where you meant 'may', 'do', or 'will'.
All 3 examples:
you were probably told not to say 'Can I use the toilet' when you meant 'May I go'
you were probably told not to say 'Can you see that building over there' when you (possibly) meant 'Do you see that building'.
you were probably told not to say 'Can you please hold this bag', when you were requesting someone to hold it, which would be 'Will you please...'
But the word 'Can' is very suitable when talking about 'the ability' to do something. For example "are you able to start tomorrow" may be said with "Can yoy start tomorrow".
Even in the 3 original examples above, using 'Can' is possible if you meant it with a shade of having the "ability to"
I know this is a Polish course, not English, but I'm sure it may help someone or another
yes, you are quite right. Of course , it is not really a 'non' word...we were just always told there was a better word to use... apart from the tin can one! But...probably I am too old fashioned, or just too old and teachers were stricter when I was a child. We would have been told to say " 'could' or 'would you be able to' start tomorrow. Maybe because in previous times english was much more formal and short cuts were frowned upon...but 'can', whatever it's definition, is here to stay. If one had to go a day without using it our brains would probably explode. But it's a fun exercise though...