Chuyển các câu sang bị động

Chuyển các câu sang bị động :
1) people believe that 13 is an unlucky nnumber
2) they know that English is an international language
3) i have heard her sing this song several times
4) people saw his steal your car
5) they say that John is the brightest student in class
6) open your book./let your book be opened
7) she advised me to sell that house
8) it is dangerous for us to take the short cut

9) they thik that he has died a natural death
10) he won't let you do that silly thing again