Do you need to measure oxygen levels before entering an enclosed space?

题库:船长 类型:最佳选择题 时间:2019-02-14 17:22:46 免费下载:《甲类船长英语考证》Word试卷

Do you need to measure oxygen levels before entering an enclosed space?
A.Yes, always
B.No
C.Not if you measure for toxicgases
D.Yes, but not if you ventilateproperly first for 24 hours

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