单项选择题
A.be accompanied by sound signals
B.not result in another close quarters situation
C.include a speed change
D.All of the above
单项选择题 When two power-driven vessels are meeting on reciprocal or nearly reciprocal courses so as to involve risk of collision，they shall be deemed to be in（）.
单项选择题 When you doubt the existence of risk of collision,（）.
单项选择题 When your vessel enters thick fog，she should sound（）every two minutes in accordance with these Rules.