Passive voice Water covers most of the Earth's surface. Have you painted the room? We must do something to avoid problems. They have built a new hospital near the airport this year. They don't advise us to go there so often.
Most of the Earth's surface is covered with water. Has the room been painted by you? Something must be done by us to avoid problems. A new hospital has been built near the airport this year. We aren't advised to go there so often.