词汇	quadrivalent element
释义	quadrivalent element 四价元素
随便看	central switch cabinet central switching Central Switching Concept central switching facility Central Switching Network Control central switching unit central swivel central symmetric matrices central symmetric matrix Central-symmetric matrix central symmetric primitive digraphs central symmetric primitive matrices central symmetric vector field central sympathetic inhibitor central syndrome central system central-system central system data base central system module central system printer central-systems central system's data base Central Tactical Air Control System Central Tactical Processing Program central tactical system