Obviously not within an Earthly month.

As you certainly know there are celestial bodies within our Solar System

whose moons have orbits, of much longer duration, and are still called 'months', so

what you asked is not really a yes/no question.

But in a month or maybe even in a week you could specialize yourself,

only in the case that you enjoy it, in the skill of asking rhetorical questions.

This skill, like so many others related to Homo Sapiens can be devolved to good or evil,

that's up to you.

I think that an accomplished polyglot could go to an English speaking country, devote his or her entire time to learning and speaking English for one month, and go from zero to upper intermediate level.   

If you already know a European language like Spanish, French , it's easier to learn English.

I think it depends on several points: Firstly, your current level or knowledge, secondly how much do you need to learn, thirdly the available time and tools you can use, finally how perfect your teacher is. But the conversational skills need much time to learn may be more than 6 months.

I think is impossible, I studied English in Oxford for um month and i didn't learn