体积为30 cm³的铜球，质量是89g，是空心的还是实心的？若是空心的，空心部分的体积是多少？(铜的密度ρ_铜＝8.9×10³ kg/m³)

The goods which are carried into and out of the territory by the same vessel or aircraft are defined as

A．transit goods
B．transshipment goods
C．through goods
D．import and export goods