A goose's neck is a little longer that than of a duck, and not so gracefully curved as a swan's.

.................. rainfall in the desert is low, it is one of the most important climatic factors in the formation of desert erosion features.

A strong swimmer, .......................................

The United States capital in Washington, D. C., developed slow, assuming its present gracious aspect, with wide avenues and many parks, only in the twentieth century.

Soapberry trees and shrubs thrive in tropical regions, and being ornamental plants in California and Florida.

......................... around us gives us vital information about our environment.

Part of the Great Plains, Kansas is famous for ............. fields of wheat.

The sidereal day is the period .................... the Earth completes one rotation on its axis.

The introduction of new species of plants into the Hawaiian islands offers an opportunity to study the responsive of a natural system to stress.