单项选择题
Each life jacket light that has a non-replaceable power source must be replaced（）.
A.every 6 months after initial installation B.every 12 months after initial installation C.every 24 months after initial installation D.on or before the expiration date of the power source
单项选择题 A person reports to you with a fishhook in his thumb. To remove it you should（）.
单项选择题 （）is used for lifting cargo.
单项选择题 Fire is under control，and（）.
