单项选择题
A.she can be observed by radar
B.she can be observed visually from the other vessel
C.she can be plotted on radar well enough to determine her heading
D.her fog signal can be heard
单项选择题 A vessel is “engaged in fishing” when（）.
单项选择题 A vessel hearing a fog signal forward of her beam has not determined if risk of collision exists. She shall reduce speed to（）.
单项选择题 A vessel has a charter party for one voyage to carry a full load of manganese from Durban，South Africa，to Baltimore，Maryland，at a stipulated rate per ton. Which type of contract is involved? （）