单项选择题
Of the following,（）is not a wind.
A.bora B.gust C.gregale D.floe
单项选择题 Risk of collision may be deemed to exist（）.
单项选择题 Risk of collision may exist（）.
单项选择题 Rule 14 describes the action to be taken by vessel meeting head-on. Which of the following conditions must exist in order for this rule to apply?（）.
