单项选择题
The radiotelegraph alarm signal is（）.
A.SOS sent three times
B.ten one-second dashes with a four-second interval between them
C.twelve four-second dashes with a one-second interval between them
D.twelve one-second dashes with a short interval between them
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相关考题
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单项选择题
The expression FIRST MAGNITUDE is usually used to refer only to bodies of magnitude（）.
A.1.5 and greater
B.1.25 and greater
C.1.0 and greater
D.0.5 and greater -
单项选择题
The expression DROP ANCHOR means（）.
A.hold anchor
B.leave anchor
C.let go anchor
D.weigh anchor -
单项选择题
The best method to stop a vessel from dragging anchor in a sand bottom is to（）.
A.reduce the length of the cable
B.pay out more anchor cable
C.back the engines
D.swing the rudder several times to work the anchor into the bottom
