1 What is the first thing you do when you back home?
2 The first thing he does when he back home is turning on the computer.
3 What is the first thing you do when you go to/after work ?
4 The first thing he does when he goes to/after work is cleaning the office.
5 What is the first thing you do when you come to the office?
6 The first thing he does when he come to the office is putting the mobilephone on the table.