My parents work in a university.
Where do your parents work?
I'm listening to you.
What are you doing?
I was at the bank 3 hours ago.
Where were you 3 hours ago?
We visit our grandparents at the weekend.
What do you do at the weekend? / When do you visit your grandparents?
I'm in the library.
Where are you?
My sister isn't at home.
Where is your sister? / Is your sister at home?