Megapolis

(a)  

Coral reef

(a)  

Free enterprise system

(a)  

Service industry

(a)  

Navigable

(a)  

Fossil fuels

(a)  

Acid rain

(a)  

Landfill

(a)  

Recycling

(a)  

Free trade

(a)  

Colony

(a)  

Democracy

(a)  

Federal republic

(a)  

Secede

(a)  

Immigrant

(a)  

Ethnic group

(a)  

Rural

(a)  

Urban

(a)  

Suburb

(a)  

National park

(a)