单项选择题
Radar makes it possible and much safer for us to sail（）.
A.in dense fog B.in boisterous weather C.in the open sea D.in rivers
单项选择题 Radar beacons are transmitters designed to produce a（）on the screens of ship’s radar sets.
单项选择题 Proper use shall be made（）radar equipment.
单项选择题 No assumptions（）on the basis of scanty information，especially scanty radar information.
