When Christopher Columbus landed in the New World,the Nort

When Christopher Columbus landed in the New World,the North American continent was an area of astonishing ethnic（种族的）and cultural diversity（差异）.North of the Rio Grande,which now marks the border between the United States and Mexico,was a populaion of over 12 million people representing approximately 400 distinct cultures,500 languages and a remarkable variety of political and religious institutions and physical and ethnic types.Compared to the Europeans,the Indian peoples were extraordinarily heterogeneous (异族的),and they often viewed the Europeans as just another tribe.
　　These varied tribal cultres were as diversified as the land the Indians inhabited.In the high plains of the Dakotas,the Mandan developed a peaceful society centered around agriculture.Only a few hundred miles away,however,in northwestern Montana,the Blackfeet turned from agriculture and began to use horses,which had been introduced by the Spaniards.As skilled riders,they became hunters and fighters and developed a fierce and aggressive culture centered around the buffalo.In the eastern woodlands surrounding the Great Lakes,the Potawatomis were expert fishermen,canoe builders,and hunters who included the Senecas and the Mohawks.In the Northeast the six Iroquois nations were among the most politicallly sophisticated people in the world,forming the famous Iroquois confederation.This confederation,with its system of checks and balances,provided a model for the United States Constitutions.
　　16.What is the main idea of the passage?
A) The political conditions in the New World.
B) The great difference among the North American Indians.
C) The conflicts and wars in the North American continent.
D) The difference between the Europeans and the American Indians.
　　17.In the eyes of the Indians,the Europeans ________.
A) were their friends
B) came from other continent
C) belonged to the same tribe as they did
D) were other Indian people
　　18.According to the passage,how was the organization of the Iroquois confederation a forerunner of the United States Constitution?
A) The Iroquois nations were among the most politically sophisticated people in the world.
B) The Iroquois confederation controlled six nations.
C) The Iroquois confederation had the system of checks and balances.
D) The Iroquois confederation was the most famous in the world.
　　19.Before horses were introduced,the Blackfeet tribes were _________.
A) brave fighters
B) aggressive hunters
C) skilled riders
D) peaceful farmers
　　20.It can be inferred from the passage that the life-style of the various American Indian tribes were influenced mostly by _________.
A) contact with other tribes
B) social development
C) environment resources
D) contact with the Europeans

B D C D C