单项选择题
Modern ships are navigated by（）（卫星）.
A.moon B.satellite C.sextant D.radar
单项选择题 Their task is to（）（驾驶） the ship safely.
单项选择题 Keep the vessel to the （）(中间)of the channel.
单项选择题 The after part of a ship is called（）(船尾) .
