6.They don’t use the house very often.
=> The house isn't used very often.
7.Do they speak French in this school?
=> Is French spoken in this school?
8.They make a lot of beautiful toys from recycled plastic.
=> A lot of beautiful toys are made from recycled plastic. 
9.The workers clean the streets everyday.
=> The streets are cleaned everyday by the workers. 
10.Do they usually hold the concerts at the university? 
=> Are the concerts usually held at the university?
11.The waiter refilled my glass
-> My glass was refilled by the waiter.
12.Is a student pinot flying that airplane?
-> Is that airplane being flew by a student pilot?