1. Has Mary opened the door?
2. Has Nick played the game?
3. Have the children washed the floor?
1. Mary has just opened the door, hasn't she?
2. Nick has already played the game, hasn't he?
3. The children have just washed the floor, haven't they?
1. Who has just opened the door?
2. Who has already played the game?
3. Who has just washed the floor?