Introduction
In the interrogative form, Wh- questions always begin with one of the wh- question words (interrogative pronouns), which show what kind of information is wanted.
The wh- questions in the present tense are used to ask for information in the present.
Form
To create a wh- question, we place an auxiliary or a modal verb after the wh- question word and before a subject.
In the present tense (both simple and continuous), we use the present forms of the auxiliary and modal verbs.
The interrogative form of wh- questions in present form have this estructure:
- with an auxiliary verb:
Wh- question word + auxiliary verb (present form) + subject + verb + …? - with a modal verb:
Wh- question word + modal verb (present form) + subject + verb + …? - without an auxiliary verb:
What/who + verb (third person singular) + …?
Which/whose + noun + verb (third person singular/plural) + …?
 
The wh- question words are: when, where, why, which, what, whose, who, whom and how.
Example
- When does the train leave?
 - Where do you buy bread?
 - Why have you got five cars?
 - Which house is yours?
 - What can I do now?
 - Whose computer is this?
 - Who speaks German in our group?
 - Whom does he like?
 - How old are you?
 
Use
The wh- words that are used to make questions are:
- when (to ask for information about time);
 - where (to ask for information about place);
 - why (to ask for a reason);
 - which (to ask for information about a preference between two or more things);
 - what (to ask for information about something);
 - whose (to ask for information about who something belongs to);
 - who (to ask for information about people, as a subject);
 - whom (to ask for information about people, as an object);
 - how* (to ask for information about the way something is done, the way something happens).
 
These questions are also called open questions because the possible answers to them are infinite.
*How does not start with wh-, but it is also considered to be a wh- question.
Summary
Wh-questions start with one of the wh- question words: what, when, where, which, who, whom, whose, why and how.
The wh- question words introduce the questions.
For example:
— “Where is the toilet?” = Where introduces an open question, because you can give an infinite number of answers.
♦ “Is there a toilet?” = Yes/no questions require short answers followed by yes or no, they are also called closed questions.
NOTE: An auxiliary (be/have…) or a modal verb (can/could/would…) must be placed after a wh- question and before a subject.
Let’s revise this content within the {Form} section. Take a look at the {Example} section that shows its use within a context.