A. 比容 B. 分子量 C. 平均密度 D. 摩尔质量
A. 正确 B. 错误
A. when they receive a special token B. when there is a carrier C. when they detect no other devices are sending D. when the medium is idle E. when the server grants acce
A. 20cm3 B. 30cm3 C. 50cm3 D. 60cm3