问题
单项选择题
Shipboard Emergency Drills must be carried out at least（）on board cargo ship.
A.Once every third year
B.Once a month
C.Once a year
D.Once a week
答案
参考答案：B
搜题请搜索小程序“爱下问搜题”
Shipboard Emergency Drills must be carried out at least（）on board cargo ship.
A.Once every third year
B.Once a month
C.Once a year
D.Once a week
参考答案：B