These are:
why, where, how, when
They are usually placed at the beginning of a question.
Examples:
l Why are you so late?
l Where is my passport?
l How are you?
l How much is that coat?
l When does the train arrive?
Notice that how can be used in four different ways:
1. meaning 'in what way?':
How did you make this sauce?
How do you start the car?
2. with adjectives:
How tall are you?
How old is your house?
3. with much and many:
How much are these tomatoes?
How many people are coming to the party?
4. with other adverbs:
How quickly can you read this?
How often do you go to London?
