what whas difficult when building the great wall of china

Four main difficulities exist.
The first one is the material. It is hard to get material to build it. The quantity demand is large. The second one is during the construction. The Wall was built on the steep mountain, so it is hard to transport the materials onto the top of the moutain. The third lies on the transporation of the food. Since the project is in remote places, so the food must be transported to the project. However, when the food reached, only a few was left and the other parts were eaten by the transportation workers. The fourth one is the safety. Wars always occured during the construction and many workers died in the wars.

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