Stage 5
Inversion in wh- questions with both an auxiliary and a main verb.
How do you say proche?
What's the boy doing?
French-speaking learners may have difficulty using Stage 5 questions in which the subject is a noun rather than a pronoun.
They may say (and accept as grammatical) 'Why do you like chocolate? 'but not' Why do children like chocolate?' In this, they are drawing on French, where it is often ungrammatical to use inversion with a noun subject.
Stage 6
Complex questions.
Question tags: (e.g. It's better, isn't it?)
Negative question: (e.g. Why can't you go?)
Embedded question: (e.g. Can you tell me what the date is today?)