单项选择题
A.installing rat guards on the mooring lines when in port
B.keeping foods protected and avoiding the accumulation of garbage
C.eliminating possible living spaces for rats when the ship is constructed
D.trapping and/or poisoning the rats
单项选择题 Multi-year ice is the hardest sea ice and should be avoided if possible. It is recognizable because of what tone to its surface color? （）
单项选择题 In order to benefit from the use of storm oil in heavy seas，the storm oil should be spread （）.
单项选择题 If your vessel has a GM of one foot and a breadth of 50 feet，what will be your full rolling period? （）