`text{39.The murdere hasn't been found by the police yet.}`
`text{40.He wasn't questioned very closely by the police.}`
`text{41.All the accounts can be done by the computer.}`
`text{42.A new school is going to be built.}`
`text{43.That building will be pulled down.}`
`text{44.The exercises won't be corrected by the teacher tomorrow.}`
`text{45.Dangerous chemicals have to be kept in the safe place.}`
`text{46.This room hasn't been used for ages.}`
`text{47.The problem can't be solved.}`
`text{48.Was an important speech made by the president last night?}`
`text{49.By whom is the passports being checked?}`
`text{50.Have you been paid by the customers?}`
