37. Bikes must not be left in the hall.
38. These documents shouldn't be left on the desk.
39. Those mountains can be seen from a great distance.
40. The seals are fed at the zoo twice a day.
41. I was asked some difficult questions at the interview.
42. My things are going to be moved next week.
43. It is believed that the Chinese invented gunpowder.
43. The Chinese are believed to have invented gunpowder.
44. The children weren't looked after properly.
45. Why wasn't I informed of the change of the plan?