During the IPv6 address resolution，a node sends a neighbor solicitation message in order to discover which of these？（）
A. The Layer 2 multicast address of the destination node
B. The solicited node multicast address of the destination node
C. The Layer 2 address of the destination node based on the destination IPv6 address
D. The IPv6 address of the destination node based on the destination Layer 2 addre
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电焊钢管的公称直径一般为（），管壁较薄，承压很低。
A. 8～10mm
B. 10～140mm
C. 20～250mm
D. 30～50mm
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