A． The cultural improvement caused the relocatio
B． Cultural development is crucial to human societ
C． The essence of the migration is the environmen
D． The discovery has changed our view completel
A． radiation of the ancient lake wate
B． radiation detected in the san
C． the fluctuation of ocean level
D． appearance of the stone tool
A． providing a panoramic view of the sea and an easier way to cross i
B． Only a small window zone of the sea as little as 2.5 miles wide could be crosse
C． The descending supplied a temporary opportunity to cross the sea easil
D． The sea was as narrow as a window so that people could cross it without effor
A． skeptica
B． enthusiasti
C． astonishe
D． indifferen