正确答案: D

两年半

题目：船舶锅炉保持入级的检验，每船装有2台及以上的主锅炉，每隔______检验一次。

解析：D

查看原题

举一反三的答案和解析：

[单选题]Watertight compartments are separated by ________

decks and bulkheads

[单选题]A segregated ballast system is a system where

all ballast lines, tanks, and pumps are independent of those used for oil