单项选择题
A.increases
B.remains the same
C.decreases
D.is unimportant and may be neglected
单项选择题 How does an icebreaker normally free a ship which has become beset while navigating independently?（）
单项选择题 Every vessel should at all times proceed at a safe speed. Safe speed is defined as that speed where（）.
单项选择题 Every vessel shall proceed at a safe speed（）the prevailing circumstances and conditions