单项选择题
The urgency signal concerning the illness of persons on board ship is（）.
A.Mayday B.Pan C.Securite D.Attention
单项选择题 There are no other vessels in the vicinity（）those at anchor.
单项选择题 There is plenty of（）at this area.
单项选择题 There is sufficient anchorage for（）at all time around the No.1 buoy and for smaller vessels around the No.4 buoy.
