Make the sentences passive: 1) people celebrated earth day on april 22 2) uncle arthur sent come stamps to his nephew. 3) russian people cook pancakes during maslenitsa week. 4) the emperor's people caught lions. 5) they brought androcles (имя) to the emperor.
Some stamps were sent to his nephew by uncle Artur.
Pancakes are cooked during Maslenitsa week by Russian people
Lions were caught by the emperor's people
Androcles was brought to the Emperor by them