年金是指每隔1个月、金额相等的一系列现金流入或流小量。( )

Where goods are to be dispatched by road, rail or air instead of by sea, the documentary credit will call for a road transport document or a rail transport document or an airway bill instead of（）.

A．a bill of exchange

B．a certificate of origin

C．a bill of lading　

D．a certificate of insurance