Why you have to put a question mark after why? example: biily: i went to the movies. jimmy: why. (why?)
That depends on the statement that prompted the question. Person A - "You should brush your teeth three times a day!" Person B - "Why?" Here, the question "Why?" actually means "Why do I have to brush my teeth three times a day?" It's an abbreviation of the full question.
Then you are wrong. Why, when, where, how, who, what.. all mean exactly the same as a '?' ? Then why aren't they interchangeable ?
examine the text below: a: i am going to the movies. b: ? a: what do you mean why. a: i am going to the movies. b: When? you cannot be asking when with ? but you can be asking why. it seems to me like if you put the ? alone you would always be asking why.