What flags are old?

How many gallons of water are in a 30 acre lake? What are the advantages of building a dam in your town? Is a coral reef cold or hot? How do you sail from Lake Ontario to Lake Erie? What is the name of the raised river bank? What ocean does the River of Silver empty into? What does the Forbidden City represent? What type of tools did john roebling use for the supension bridge? What is the lifespan of a bridge? What is happening to the width of the Atlantic ocean? What is a beach that projects like finger out into the water? What river runs through Chicago? What are Two countries that do not have an ocean on any of their boundaries? How does the great garbage patch affect the coral reefs? Did Vitus Bering have a family? What is the use of tower? Where are do most tropical rainforests exist? What islands are along the equator in the Indian Ocean? What are canal-like structures used to carry water to the cities? Which ocean does not touch Asia?