烧结矿按其含铁量分为（），一等烧结矿的含铁量应大于60%以上。
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发生火灾后对消防安全有重大影响的部位不包括（）。
A. 通信设备机房
B. 变配电站(室)
C. 消防控制室
D. 消防水泵房
（）of the following need NOT be entered in the Official Logbook（）.
A. The testing of the internal combustion engine driven emergency generators at least once each month the vessel is navigated
B. The testing of storage batteries for emergency lighting and power systems once each 6 months the vessel is navigated
C. The actual draft when the vessel arrives in salt water after departing a port
D. The testing of the line-throwing appliance once every 3 month
2048kbit/s信号接75欧姆负载时，脉冲幅度的标准电压值是（）V。
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