68. Different kinds of flowers were planted by her father.

69. A speech is being made by the Prime Minister at the moment.

70. How many days were spent finishing the work?

71. One of my teeth was pulled out by the doctor yesterday morning.

72. Sandwiches are usually brought to him by his wife at lunch time.

73. The light went out while a cup of tea was being made.

74. When she went to Barcelona, Spanish was learnt by her.

75. Many experiments were made by the students of chemistry last week.

76. For the past years, all my washing has been done by hand.

77. A nest has been built in the porch by a pair of robins since last week.

78. She is said to be the best singer in this town.

79. It's believed that he will be the winner.

80. Tom is thought to steal food in the market 3 days ago.

68) Her father was planting different kinds of flowers in the garden.

=> Different kinds of flowers were planted by her father.

69) The Prime Minister is making a speech at the moment.

=> A speech is being made by the Prime Minister at the moment.

70) How many days did she spend finishing the work?

=> How many days were spent finishing the work?

71) The doctor pulled out one of my teeth yesterday morning.

=> One of my teeth was pulled out by the doctor yesterday morning.

72) His wife usually brings him sandwiches at lunch time.

=> Sandwiches are usually brought to him by his wife at lunch time.

73) The light went out while I was making a cup of tea.

=> The light went out while a cup of tea was being made.

74) When she went to Barcelona, she learnt some Spanish.

=> When she went to Barcelona, Spanish was learnt by her.

75) The students of chemistry made many experiments last week.

=> Many experiments were made by the students of chemistry last week.

76) For the past years, I have done all my washing by hand.

=> For the past years, all my washing has been done by hand.

77) A pair of robins has built a nest in the porch since last week.

=> A nest has been built in the porch by a pair of robins since last week.

78) They say that she is the best singer in this town.

=> She is said to be the best singer in this town.

79) They believe he will be the winner. It

=> It's believed that he will be the winner.

80) People think that Tom stole food in the supermarket 3 days ago.

=> Tom is thought to steal food in the market 3 days ago.