9.4.3.3 Interrogative
Use this domain for words that a speaker uses to indicate that he is asking a question. English has no question word, but other languages such as Japanese do.
What words indicate that the sentence is a question?
(Japanese) ka? 'a particle coming at the end of a sentence to indicate that it is a question'
English has an interjection that is added to a statement that has the effect of questioning something about it.