确定整个货币制度的基础因素是（）

A.货币金属

B.货币单位的确定

C.确定本位货币

D.确定辅币材料及其铸造和流通

The best method to stop a vessel from dragging anchor in a sand bottom is to（）.

A.reduce the length of the cable

B.pay out more anchor cable

C.back the engines

D.swing the rudder several times to work the anchor into the bottom