单项选择题
In the International Code of Signals，the code signal meaning I require immediate assistance is（）.
A.AE B.CB C.DX D.CP
单项选择题 In order to pay out or slack a mooring line which is under strain，you should（）.
单项选择题 In order to maintain a safe speed at all times，any necessary alterations of speed must（）.
单项选择题 In order to detect rot in manila lines，you should（）.
