Thepassageismainlyabout_
A、theusesoflifepreserversAccordingtothepassage，alifebefirstofall
A、adjustableUnitedStatesCoastGuarddoesNOTrequirethelifepreservertobemade_
A、withasfewstringsaspossibleBy“theuninitiatedindividual”(Para.1，Line.4)theauthorreferstotheperson
A、whohasnotbeeninstructedhowtousealifepreserverWhatwouldhappenifapersonweresupportedbythelifepreserverinawrongposition?
A、Thewaveswouldmovehimbackwards