单项选择题
The backup system on an electric start survival craft is a（）.
A.hydraulic system B.pneumatic system C.spare battery D.hand crank
单项选择题 Symptoms of sea sickness include（）.
单项选择题 Symptoms of heat stroke are（）.
单项选择题 Sign(s) of respiratory arrest requiring artificial respiration is(are)（）.
