横向
1
Flat grassland in tropical regions
6
Chain or group of islands
7
Large natural stream of water
9
Largest river in South America
纵向
2
Land surrounded by water
3
Landform where river meets the sea
4
Region surrounding the North Pole
5
Deep narrow valley with steep sides
8
Large area covered with trees
10
Wearing away of land by water or wind
11
Imaginary line around the middle of Earth
12
Mountain that can erupt with lava