It is important that you do not expel the air or the barium. The air is used to expand the walls of the colon for a more detailed look at the lining of your colon. After the barium and air is in, the technologist will take a series of X-rays of your colon. You will be asked to hold your breath and remain still during the picture. An imaging physician will review the images to make sure that they are sufficient to make a diagnosis. If they are not, more pictures may be taken.
However, it is not known how the builders got the huge wooden support columns into position. Unlike western architecture, in ancient Chinese wooden architecture, the wall only defined an enclosure, and did not form a load-bearing element. Buildings in China have been supported by wooden frames for as long as seven millennia.
Why was the Great Wall of China bulit? The Great Wall of China was built to protect China from its enemies and invaders from the North, especially the Mongols. The Mongols were a tribal group that would regularly conduct raids into China. Despite the wall, the Mongols eventually conquered China. The Wall also kept Chinese citizens from leaving China.