横向
1
Wearing away of land by water or wind
4
Landform where river meets the sea
7
Vast body of salt water
8
Largest ocean on Earth
9
Flat grassland in tropical regions
10
Land surrounded by water
11
Largest river in South America
12
Seasonal heavy rainfall
纵向
2
Steep rock face at edge of land
3
Distance east or west of prime meridian
5
Large natural elevation of earth
6
Cold treeless Arctic plain
13
Raised area of land, smaller than a mountain