There are not that many words in English that can, without any change in their grammar structure, be both a verb, a noun, several slang nouns, and a transitive verb (that is the one that derived from the noun). The verbal meaning of "can" came to our language from either Old High German "kan" (in modern German it is "kann" and has the same meaning as English "can") or from Old English's "cunnan" which meant "to know more". If we think for a moment about the meaning of "being able to do something" – as "can" prescribes us to behave – we cannot deny the fact that it must absolutely involve some knowledge of how to do that. Thus I tend to believe that Old English's origin of "can" is more convincing.
             Since every subject's examination starts with identification and understanding of
             the matter we start by looking up the word "can" in the Merriam-Webster's Collegiate Dictionary and see that it has several usage variants, many of which include phrasiological participles. The first meaning and the most obvious and common usage of "can" to us all is – "to be able to do something, to know how to do something". In this context the commonly used synonym of "can" is "may", but often the speaker does not know the exact meanings of two words, which are quite confusing, and mismatches them in his writings or speaking. The controversy of these words usage is in the fact that both express the idea of giving or requesting permission, but at the same time the word "can " is more concerned with somebody's individual ability to perform a task, while "may" is a more formal way of dealing with the matter and asks for another party's permission to do something. I would like to stress here that even though both "can" and "may" are ...