单项选择题
A.the towing vessel should slip first
B.the vessel towed should slip first
C.they should slip simultaneously
D.either vessel may slip first
单项选择题 You are underway and pass by a lighthouse. Its light，which was white since you first sighted it，changes to red. This means（）.
单项选择题 You are the first vessel to arrive at the scene of a distress. Due to the volume of traffic on the radio，you are unable to communicate with the vessel in distress. Which action should you take?（）
单项选择题 You are on a multiple-product chemical tanker with orders to load diethylamine. What is NOT a requirement for transporting this cargo?（）