填空题
[听力原文] 11-15
(11) All mammals, except man and the monkey, swim naturally from birth．For man，like the monkey，it is not instinctive to float．Deaths by drowning arecommon everywhere．(12) In the United States alone, about 7,000 children under four drown each year.Everything possible is done to prevent such tragedies．(13) One solution that is particularly effective is to teach children to swim while they are still babies. Most largetowns in Florida and California akeady run lessons forbabies and infants． (14) The idea has spread to Europewhere，in several countries，special courses are now arranged for children from seven to twenty-four months．(15) The first step is to eliminate the child’s fear of thewater. Next, he’s taught to float. Once he can do thisnaturally and without fear，the child grasps the technique and can push forward himself through the water．