Ответ:
Had you completed the task?
Had Mary already told the truth?
Had you completed the task before he proposed his help?
What had Mary told when he entered the room?
Whom had Mary told the truth when he entered the room?
How had you completed the task before he offered you help?
When had you completed the task?
Had you ever seen her before?
Had he already left when James decided to talk to him?
What had Mary told when he entered the room?
вот)