The man in black was about to set fire to the house ____ the police came. 

 Unfortunately, women were not admitted to university in the past, ______, nowadays, they have got equal rights.

It’s important to give the babysitter an emergency phone number ___ the children get hurt or sick.

You have failed two tests.You'd better start working harder, ________you won't pass the course.

—Did you return Fred’s call? —I didn’t need to ____ I’ll see him tomorrow.