单项选择题
The two vessels underway may collide with（），if they don’t take immediate measures.
A.One to another B.One the other C.Each the other D.Each other
单项选择题 The term restricted visibility，when used in the Rules，refers to（）.
单项选择题 The term PROLONGED BLAST refers to（）.
单项选择题 The Rules state that risk of collision shall be deemed to exist（）．
