The standard (IEEE 802) format for printing（）in human-friendly form is six groups of two hexadecimal digits, separated by hyphens (-) or colons (:), in transmission order, e.g.01-23-45-67-89-ab, 1:23:45:67:89:ab. This form is also commonly used for EUI-64.

A．hard disk logical block address

B．IP address

C．mail address

D．MAC address

杆件的应力与杆件的（）有关。

A.外力

B.外力、截面

C.外力、截面、材料

D.外力、截面、杆长、材料