出版說(shuō)明 To the Teacher Steps for the Reader Vocabulary Words and Definitions Concept I: Common Needs Create Groups In Search of Freedom A Migration to America Water in the America Water in the Desert "Doctors of the Deep" One Roof,Many People A New Place to Shop Together for the Games A Center of Learning Earthequake! Saving Prince William Sound They Help Others Photos That Tell Stories Partners A Dam with Many Uses City Planners Fire Fighters Presserving the Past A Mansion for All of US the Wise Chief Concept II:Groups Continue Because of Some Benefits A Capital Bulit to Order The Wilderness Capital Monkeys That Look Like Dogs Help in Time of Trouble They Benefit the Community The Many Owners A Very Large Family "Children of the Forest" The Farmers of cades Cove Their Living Came from the Sea Ten Wooden Pins The Heart of a Neighborhood Mailbags First,Passengers Second Houses from Factories A Wpinster's Work A Congress for the Colonies Pictures by the Millions Part-time Actors The Giant with 100 Eyes Concept III : The Group Gets Bigger As More Things Share the Benefits …… Concept IV:When the Size of a Group Gets So Large That Benefits Do Not Reach Its Members,Smaller Groups Are Formed