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
单项选择题 PAN-PAN repeated three times over the radiotelephone indicates which type of message will follow?（）
单项选择题 In radiotelephone communications，the prefix PAN-PAN indicates that（）.
单项选择题 Fog forms when the air（）.
