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（）.
A.crossing situation B.head-on situation C.restricted visibility D.overtaking situation
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.
单项选择题 Where does the look-out man stand?（）.
