The direct reason for specialization is______.A．the development in scientific activitiesB．

The direct reason for "hidden harmony" in human culture is ______.A．dynamic balanceB．stati

What is mentioned as a direct reason people moved into the Great Plains in the 1880s？A．The

His principal reason for making the journ

His principal reason for making the journ

The results of the study indicate the reason for

The results of the study indicate the reason for