单项选择题
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
The expression FIRST MAGNITUDE is usually used to refer...
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
The expression DROP ANCHOR means（）.A.hold anchorB.leave...
单项选择题The expression DROP ANCHOR means（）.
A.hold anchor B.leave anchor C.let go anchor D.weigh anchor
The best method to stop a vessel from dragging anchor i...
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
