钙硬度表示水中()的含量。镁硬度表示水中()的含量。
参考答案:钙离子;镁离子
海关依申请扣留侵权嫌疑货物的,其最长扣留期限为,自海关扣留侵权嫌疑货物之日起()个工作日内。
A.15
B.30
C.20
D.10
Which statement is TRUE().
A.GMDSS radio logs are required to contain entries pertaining to all incidents connected to radio communication service which appear to be of importance to the safety of life at sea
B.All distress communications must be entered in the GMDSS radio log
C.Both of the above
D.None of the above