二等, 二流second class
主动脉瓣第二音aortic second heart sound, A2
a. 第二好的second-best
香农第二编码定理second Shannon coding theorem【通信】
二阶平稳的second-order stationary【数】
回头率rate of second glance
后茬罪second crop
第一秒用力呼气量占用力肺活量百分率percentage of forced expiratory volume in first second to forced vital capacity\nFEV1\n医