横向
1
Metal that replaced bronze in tools
3
Formal agreement between nations
4
Ancient Mesoamerican civilization
7
Person owned as property
8
Object made by humans from the past
9
Person who buys and sells goods
10
Union formed for mutual benefit
纵向
2
Person who travels to discover new lands
4
Government ruled by a king or queen
5
Military conflict or fight
6
Uprising against authority