We all know that we live in a complex world .Although the technics of the human beings are developing all the time , we still got so many unsolved problems. Among all of this puzzles , UFO is one of the most noticable things.
Now as everybody knows ,UFO is what we call Unknown Flying Object for short.For a period of time ,once we mentioned UFO , we always communicate it with high-tech ,extra-terrestrials ,outter space culture and many other exciting things .
