No one has used this sewing machine for several months

->this sewing machine hasn't used for several months.

the children are drawing pictures about their ideal world

->pictures are being drawn by the children about their ideal world

they awarded him the Nobel prize for medicine in 1946

-> the Nobel prize was awarded to him for medicine in 1946

we saw him leave the office at 6 o'clock this morning

->He was seen leaving the office at 6 o'clock that morning

you ought to water these plants once a week 

->these plants ought to be watered once a week by you

people saw her driving a car near the bridge

-> she was seen driving a car near the bridge

the said that he was the richest man in the town

-> he was said to be the richest man in the town

scientists began to carry out researches on AIDS in 1981

->researches on AIDS was begun to carry out in 1981 by scientists

everybody believed that he had died of lung cancer

-> he was believed to have died of lung cancer

people can't learn a foreign language in a short time

-> a foreign language can't be learned in a short time

did anyone ask any question about me

->was any question asked about me?

the robbers forced the bank manager to hand over the money

-> the bank manager was forced to hand over the money by the robbers

they let us go

-> we are allowed to go by them

some people think he is a dangerous criminal

-> he is thought to be a dangerous criminal

no one told me the truth

-> i wasn't told the truth