单项选择题
An obstruction on a helideck is any object that might present a hazard to the（）.
A.rotor blades and landing gear B.unloading of passengers C.loading of cargo D.pilot's visibility
单项选择题 AN ILLNESS PREFERABLY OF AN INFECTIOUS NATURE SEIZING MORE THAN TWO PERSONS ON BOARD AT THE SAME TIME defines（）.
单项选择题 Aboard a survival craft，ether can be used to（）.
单项选择题 A towline should be fastened to（）.
