这五句改为被动语态怎么改；1：our teacher helps us study better.2：where did you buy the bus?3：will the boy make a car?4：did your sister visit her grandpa?5：my father told me a good story.

1、Our teacher helps us study better.
We are helped by our teacher to study better.
2、Where did you buy the bus?
Where was the bus bought by you?
3、Will the boy make a car?
Will a car be made by the boy?
4、Did your sister visit her grandpa?
Was your grandma visited by your sister?
5、My father told me a good story.
Were you told a good story by your father?