单项选择题
AN ILLNESS PREFERABLY OF AN INFECTIOUS NATURE SEIZING MORE THAN TWO PERSONS ON BOARD AT THE SAME TIME defines（）.
A.Disease of Crew B.Crew illness C.Group illness D.Mass disease
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（）.
单项选择题 A shipmate chokes suddenly，cannot speak，and starts to turn blue. You should（）.
