单项选择题
Each hand portable，semi-portable and fixed fire extinguishing unit on a ship must be tested and inspected at least once every（）.
A.six weeks B.six months C.twelve months D.two years
单项选择题 Each hand portable fire extinguisher on a ship must be marked with（）.
单项选择题 Each fire pump on a tanker must have a pressure gauge located at（）.
单项选择题 Each fire hose coupling on a ship must have threads that meet the specifications of the（）.
