Complete using the correct form of the words :
BE , DISAGREE , DO , INCLUDE , KNOW , LOOK , SEE , SEEM , UNDERSTAND.

Everyone (1) ..............................that humans have been flying for only a few hundred years. But (2) ................... it possible that ancient civilizations also had the ability and technology to fly? In the Nazcan Desert in southern Peru, there are hundreds of lines which an ancient culture drew in the dust. On the ground, they just (3) .......... like straight lines. But when you (4) ............................them from the air, you (5) ............................ exactly what they are. They are incredible and enormous pictures. The pictures (6) ............................animals, birds and symbols. One bizarre theory, which most mainstream scientists (7) ............................ with, is that the people who made the lines thousands and thousands of years ago flew above the lines in balloons. It (8) ....................... incredible, but a few people (9) ............................ believe it`s possible.