Where :
– Where do you study ?
– Where do you live ?

What :
– What are you studying ?
– What do you like to study ?

When :
– When do you like to study ?
– When did you arrive at the library ?

Why :
– Why do you work at night ?
– Why do you study in the morning ?

Who :
– Who did you study with ?
– Who did you see yesterday ?

How :
– How can you work in the mornings ?
– How can you work at night ?