`~rai~`
`text{5.We are being followed.}`
`text{6.Their teachers are going to be sent letters.}`
`text{7.It is known that the expedition reached the South Pole in May.}`
`text{or:The expedition is known to have been reached the South Pole in May.}`
`text{8.It has to be seen to be believed.}`
`text{9.Little boys used to be made to climb the chimneys to clean them.}`
`text{10.He doesn't like being laughed at.}`
`B.`
`text{1.An orange can't be eaten if it hasn't been peeled.}`
`text{2.You can't be put in prison if you haven't been tried.}`
`text{3.He was brought up by his grandfather and his education was got in HCM City.}`
`text{4.Before printing was invented,everything had to be written by hand.}`
`text{5.No thing has been moved since you were sent away to be cared.}`
`Ex 8:`
`text{1.A student threw the stones.}`
`text{2.A strong police guard was escorting the referee from the football field.}`
`text{3.Egyptian and Greek sailors have used carrier piegons.}`
`text{4.A sudden increase in water pressure would break the dam.}`
