The Great Wall is not a single wall but a series of fortifications built over centuries.

长城不是单一的墙，而是几个世纪以来建造的一系列防御工事。

同一单元的其他句子

• The Eiffel Tower is an iconic landmark that attracts millions of visitors each year.埃菲尔铁塔是一个标志性的地标，每年吸引数百万游客。
• Have you ever seen the Great Wall of China at sunrise?你见过中国长城日出时的景象吗？
• The Statue of Liberty symbolizes freedom and democracy for many people.自由女神像对许多人来说象征着自由和民主。
• Don't forget to take a selfie in front of the Sydney Opera House.别忘了在悉尼歌剧院前自拍。
• The Taj Mahal is renowned for its stunning white marble architecture.泰姬陵以其令人惊叹的白色大理石建筑而闻名。