16、A regular service between fixed sea ports is（ ）．

A．tramp service

B．liner service

C．r to r service

D．forwarding service

17、The（ ）can not be transferred to third parties．

A．straight B/L

B．direct B/L

C．shipped B/L

D．order B/L

18、The（ ）is the most important document for air cargo transporion．

A．B/L

B．AWB

C．SWB

D．NOR

19、To the individual consignors， the consolir is the（ ）while to the actual carrier， he is the （ ）．

A．carrier/actual carrier

B．carrier/consignor

C．consignor/carrier

D．consignor/consignor

20、Documentary credit means payment inst（ ）．

A．ship

B．cargo

C．documents

D．money