单项选择题
Radar reflectors are required for（）.
A.all fishing vessels over 39 feet in length B.sail-propelled fishing vessels C.all fishing vessels of less than 200 GT D.wooden hull fishing vessels with a poor radar echo
单项选择题 PPI is（）.
单项选择题 Although manual plotting for CPA works well，the workload can become overwhelming when confronted with（）.
单项选择题 （）typically extends from close as 0.1 nautical miles out to 32 NM.
