One of the very important documents in the foreign trade business is BL. B/L is the abbreviation for ______.

A．Bill of Lading
B．Commercial Invoice
C．Buying Contract
D．Letter of Credit

UMG8900参与级联的单板中不同时提供级联部分和主机两部分的有（）。

A、TNU

B、TCLU

C、NET

D、BLU