questions words

we use the questions words when we' like to make some senteces to some person etc.

the questions words can be:

what's your last name?
who is your teacher?
how many brother do you have
why don't you like the pasta?
where are your best friend from?
when do you come to france?

this words only can be use for make questions, except when. for example:

when i was eight years old, i couldn't ride a bike alone.
here i have a sentence, but you can see that it isn't questions