A．金属导线中
B．光纤中
C．真空中
D．空气中
BD
完整的交接手续中不包括（）。
A.接受货物
B.接受文件
C.签署单证
D.发货清单
–Where is Tom? --He _______ the USA. He _______ back in two months.
A. has gone to; comes B. has bee to; will be
C. has been to; comes D. has gone to; will be
