Have UFOs and aliens visited Earth?

Here are some of their stories:

• In 1964, Policeman saw a strange machine and two strange 'men' weren't from Earth. The machine disappeared into the sky. All the plants on that piece of ground were dead.

• In 1995 a Farmer saw the some that policemen.

• In the 1100s a boy and a girl completely green were found of Woolpit.

• In Roswell found pieces strange of metal. The military decided that it was from a UFO. But after relate a different stories that don't believe. So we will probably never know the true story.

• In 1961, the family Hill saw a large yellow thing. Then they suddenly felt very tired and woke up an hour later in a different place.