问题
单项选择题
Emergency escape breathing device on board shall have a duration of service no less than（）.
A.20 minutes
B.15 minutes
C.10 minutes
D.5 minutes
答案
参考答案：B
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Emergency escape breathing device on board shall have a duration of service no less than（）.
A.20 minutes
B.15 minutes
C.10 minutes
D.5 minutes
参考答案：B