A.V-shaped ripple with the point of the V pointing upstream
B.V-shaped ripple with the point of the V pointing downstream
C.small patch of smooth water on a windy day
D.smoothing out of the vessel's wake

A.administer oxygen
B.immediately check his pulse and start CPR
C.make the victim comfortable in a bunk
D.immediately give a stimulant，by force if necesssary