单项选择题
It may be found that，in certain circumstances，Radar Beacon can cause unwanted interference particularly（）.
A.at close range B.at end on situation C.at head on situation D.at crossing situation
单项选择题 It is dangerous for vessels without the use of radar（）the estuary.
单项选择题 Induced magnetism is found in（）.
单项选择题 If several fixed navigational lights are visible at the same time，each one may be positively identified by checking all of the following EXCEPT what against the Light List?（）
