单项选择题
A.tightened B.secured C.unfastened D.loaded
（）operation, any obstacles in the way of hatches must b...
单项选择题（）operation, any obstacles in the way of hatches must be removed and cleaned.
A.Before B.During C.After D.Within
Each （）consists of two or more panels.A.coverB.hatchC.d...
单项选择题Each （）consists of two or more panels.
A.cover B.hatch C.derrick D.winch
Keep a close watch on（） cargo.A.valueB.valuationC.valua...
单项选择题Keep a close watch on（） cargo.
A.value B.valuation C.valuable D.All above
