改为被动句。 They usually close the Art Gallery on public holidays. No one has ever beaten

为被动句。
They usually close the Art Gallery on public holidays.
No one has ever beaten him at chess before.
Someone changes the notices on the board every week.
They emptied the bag of its contents.Then they filled it up with books.
Nobody told me that it was dangerous to use that machine.
Did they questions you at the police-station.
They had sent Mr Wang abroad on a business trip.
You must send in this from before the end of the month

1 the art gallery is usually closed on public holidays
2 he has never beaten by anyone at chess before .
3 were you questioned by them at the police station
4 mr wang had been sent abroad by them on a business trip
5 this form must be sent in before the end of the month
6 notices on the board are changed by someone