单项选择题
In order to ensure that a RACON signal is displayed on the radar，you should（）.
A.increase the brilliance of the PPI scope B.turn off the interference controls on the radar C.use the maximum available range setting D.increase the radar signal output
单项选择题 In a crossing situation，the stand-on vessel should normally（）.
单项选择题 You may find the time of slack water after low water in a certain port from（）.
单项选择题 The satellite system of GAMDSS comprise（）.
