单项选择题
After using a C02 portable extinguisher,it should be（）.
A.put back in service if some CO2 remains B.hydrostatically tested C.retagged D.recharged
单项选择题 All dunnage planks and mats must be sent to board（）commencement of loading.
单项选择题 All echo-sounders can measure the（）.
单项选择题 All electrical appliances aboard a vessel should be grounded to（）.
