Small floes of rough,hummocky sea ice capable of damaging a vessel().

A . can usually be detected by radar in a smooth sea at a range of 4 to 6 kilometers B . are indistinguishable from sea return on the PPI C . are invisible to radar when covered with a thick layer of snow D . are usually seen at night before they are close enough to provide a radar echo

时间:2022-09-30 09:55:01 所属题库:狭水道、冰区与运河航行题库

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