He believes that he saw a _____ flying in the sky last night. He was scared that the aliens would appear and take him out of the earth

47. He believes that he saw a _____ flying in the sky last night. He was scared that the aliens would appear and take him out of the earth.
A. ship B.motorhome C lantern D. UFO
48. He's living in a_____ on a large river. It's very convenient for him to catch fish every day.
A. palace B.airplane C.houseboat D. flat
49. There are a lot of _____in her big city. I can't count how many floors there are
. A. skyscrapers B. spaces C. programmes D. tractors
50. She can keep vegetables and fruits fresh in her______ during a long time
. A. helicopter B. modern fridge C. electric cooker D. spaceship