CONJUGATION- a piece of cake-

Just make some changes by putting WILL, BE- ING, HAVE- ed, S and ED appropriately.
Who will call?
Who will be calling?
Who will have called?
Who will have been calling?
Who has been calling?
Who has called?
Who had been calling?
Who had called?
Who is calling?
Who was calling?
Who calls?
WHo called?