题目内容：
The Air Waybill(AWB) is the most important document for a batch of air freight goods.The AWB number is the identification of each consignment.It comprises three parts: （ ）.
A．a three -digit prefix identifying the carrier B．the main portion identifying the consignment
C．the main portion identifying the carrier
D．the last check digit for accounting and security purposes
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答案解析：