In1947,an American pilot said that when he was flying in the sky he had seen nine strange things.They looked like saucer.Then （newspaper ) reported his story.After that,more people all over the world said they had seen .strange things.But people could not decide on what the things were or where they came from.So they (called ) them UFOs (不明飞行物).
In 1973,two fishermen said that they when they were (fishing ) by a river they had seen a UFO.It looked like an egg.There was three figures like men in it.They had no eyes and their mouth were long and narrow.Their noses and ears were (strange ) too.
Perhaps some people make a mistake,but pilot and astronaut do not usually make mistakes of this kind.Captain ED Mitchell,the sixth men to walk (on ) the Moon,said in 1974 that he had seen some flying saucers.He said those flying things were perhaps visiting the Earth from other worlds in space.
There are many stories about UFOs.However,(nobody ) knows whether they are true or not.