单项选择题
Areas which cannot be scanned by the radar of the vessel because they are shielded by parts of its superstructure, masts,etc means（）.
A.blind sectors B.sheltered area C.unseen area D.unscan ble area
单项选择题 Compatibility of goods states（）.
单项选择题 Course directed by the 0SC or CSS to be steered at the beginning of a search is（）.
单项选择题 Engine room is（）fire.
