Radar is of great help to ship in poor（）(能见度).

单项选择题Navigators use navigational aids, such as（）（罗经）.

A.sextant
B.binoculars
C.compass
D.loran

单项选择题（）（电罗经）can tell us true north.

A.VHF
B.Radar
C.Chart
D.Gyro-compass

单项选择题Officers observe ships with a pair of （）（望远镜）.

A.sextant
B.binoculars
C.compass
D.radar

单项选择题The （）（天线）is like a dish.

A.line
B.thread
C.aerial
D.wire

单项选择题This is a radio （）（测向仪）.

A.compass
B.direction finder
C.loran
D.sextant