We ask wh_ word questions to find out more particular information about who, what, how, when, where, how much, how many, etc. Those questions begin with a special question word.

Here is a piece of information:

Mary bought that book in Smiths.

We can ask one question about the subject:

            Who bought that book?                                              –                    Mary did

(The subject of the question is who)

The basic pattern for this type question is:

Question word  +  verb  +  object

We can ask two questions abou the object:

What did Mary buy?                                               –                   That book

Where did Mary buy that book?                              –                   In Smiths

The basic pattern for this type of question is:

            Question word  +  auxiliary  +  subject  +  verb


Most wh_ word questions are made in this way:

Question word                          auxiliary                       subject             verb
How many                                did                                you                   buy?
How often                                 have                             you                   been there?
How                                         can                               I                       get in touch with you?
Which                                      did                                you                   choose?
Who                                         could                            we                    ask to help?
Why                                         would                           you                   like to go?
Which floor                              do                                you                   live on?
Whose car                                were                             you                   driving yesterday?