A. 根据句子意思及首字母提示完成单词：
1. Today the g _____ and many people realize the importance of saving these old city walls.
2. How did the a ____ Egyptians build the Great Pyramid?
3. Since then, people r _____ the Great Wall as a symbol of the Chinese nation.
4. The Great wall is a s ____ of the Chinese nation.
5. The Amazon River it the l ______ river in the world.