横向
1
Largest river in South America
4
Ridge of rock or coral near the surface
5
Largest ocean on Earth
7
Flat grassland in tropical regions
8
Wearing away of land by water or wind
10
Land surrounded by water on three sides
纵向
2
Deep narrow valley with steep sides
3
Line dividing two countries
6
City that is seat of government
9
Region near the equator