Grammar Assignment

Write me a grammar that accepts an english language yes-or-no question, but nothing else.
It should except things like
	Is he dead?
	Is he going to the store?
	Is he a boy?
	Is he going
But not
	Is he?
	Is he he dead?
	Is he going to?
	Dead boy is he?


You may assume that VERB NOUN PROPOSITION ARTICLE GERUND and so on are all defined.