单项选择题
After the boat is at the top of the davit heads，the davit arms begin moving up the tracks and are stopped by the（）.
A.hoist man B.limit switch C.brake handle D.preventer bar
单项选择题 A vessel may be unable to take proper and effective action due to the speed（）too high or，in some circumstances，too low.
单项选择题 A tourniquet should be used to control bleeding ONLY（）.
单项选择题 Preventer bars are fitted on lifeboat releasing hooks to prevent（）.
