Antiseptics are used principally to（）.

单项选择题An inflatable liferaft is floating in its container，attached to the ship by its painter，as the ship is sinking rapidly. Which action should be taken with respect to the liferaft container? （）

A.Cut the painter line so that it will not pull the liferaft container down
B.Swim away from the container so that you will not be in danger as it goes down
C.Take no action as the pull on the painter will cause the liferaft to inflate and open the container
D.Manually open the container and inflate the liferaft with the hand pump

单项选择题An indirect radar echo is caused by a reflection of the main lobe of the radar beam off the observer’s vessel. Which of the following is NOT a characteristic of indirect echoes? （）

A.Their bearing is almost constant，even when the true bearing of the contact changes appreciably
B.They always appear on a bearing of 90°From the true bearing of the contact
C.The indirect echoes usually appear in shadow sectors
D.When plotted，their movements are usually abnormal

单项选择题An icebreaker may use the code letter “K” to remind ships of their obligation to listen continuously on their radio. This signal may be made by any of the following EXCEPT（）.

A.sound signal
B.light signal
C.visual signal
D.radiotelephone

单项选择题An icebreaker displaying a flag hoist which consists of the code letters “WO” (Whiskey Oscar) is indicating that（）.

A.icebreaker support is finished
B.icebreaker support is commencing
C.the icebreaker is icebound
D.the icebreaker is beset

单项选择题An icebreaker assisting a vessel through an ice field would display a visual signal consisting of the code letter “E” (Echo) to signify that “（）”.

A.I am altering my course to starboard
B.I am altering my course to port
C.I am operating astern propulsion
D.My vessel is stopped and making no way through the water