单项选择题 If you are the Master of a towing vessel whose only working radar no longer functions，what must you do?（）

单项选择题 If a fixed foam firefighting system on a ship is not of the premix type，a sample of the foam liquid must be tested by（）.

单项选择题 Fire protection regulations for towing vessels require that all crew members participate in drills and receive instruction at least once a month. Who is responsible for ensuring that this takes place?（）