The human ______ is the center of higher nervous activity.

B.mind

C.head

D.thought

European in the 15th century have long been known as Indians because 【M2】______

of the belief prevalent at time of Columbus that the Americas were the 【M3】______

outer reaches of the Indies. Most scholars agree that Native Americans

came into the Western Hemisphere from Asia by the Bering Strait in a 【M4】______

series of migrations. From Alaska they spread to the east and south. 【M5】______

Several separate waves of migration are said to count for the many native 【M6】______

linguistic families, while the common origin used to explain the physical 【M7】______

characteristics that Native Americans have in common--Mongoloid

features, coarse, straight, black hair, dark eyes, sparse body hair, and

a skin colour range from yellow-brown to reddish brown. Many scholars 【M8】______

accept evidence of Native American existence in the Americas back more

than 25,000 years. In pre-Columbian times the Native American

population of the area north of Mexico is estimated to be between one and 【M9】______

two million. From prehistoric times until recent historic times there were

roughly about six major cultural areas, excluding that of the Arctic i. e. ,【M10】______

Northwest Coast, Plains, Plateau, Eastern Woodlands, and Southwest.

Information about particular groups can be found in separate articles and in

separate biographies and subject articles.

【M1】

A、Thermodynamics

B、Quantum chemistry

C、Kinetics

D、Statistical mechanics

B.essential

C.precious

D.worthwhile

B.look after

C.look out

D.see to it

B.Yes, its as quiet as we expected

C.Youre so considerate

D.No, the prices reasonable

B.three times

C.three time

D.time three