单项选择题
A.boarding and operating procedures
B.maintenance schedule
C.navigational systems
D.fuel consumption rates
单项选择题 All vessels（）size shall, whether in a fairway or not,observe the International Regulation for Preventing Collisions at Sea 1972.
单项选择题 An ABC dry chemical fire extinguisher would be least effective against a fire in（）.
单项选择题 An advantage of a dry chemical over a carbon dioxide fire extinguish is its（）.