对首次入网的（）避雷器或者运检部门认为必要的应进行出厂验收。
A. 1000kV及以下
B. 500kV及以下
C. 330kV及以下
D. 750kV及以下
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像管的主要功能是什么？有哪几部分组成？像管和摄像管的最大区别是什么？
How do you determine the weight of the vessel that is supported by the ground when a vessel has run aground?（）.
A. This requires extensive calculation and is usually performed only by a naval architect not by a ship's officer
B. Determine the point where aground and the draft at that point，then calculate it using the grounding formula
C. Use the hydrostatic tables and enter with the mean draft before grounding and the mean draft after grounding
D. Use the inclining experiment formula and substitute the change of trim for the angle of list
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