单项选择题
This is a radio （）（测向仪）.
A.compass B.direction finder C.loran D.sextant
单项选择题 The ship’s（）（天文钟）is a very accurate clock.
单项选择题 The bosun is good at（）(打绳结).
单项选择题 The third officer is （） (负责)the fire-fighting equipment.
