sentence: People sail in a boat in a river, and a man pulls a string of a person that sets up to perform water ski. sentence:  Then, the person water ski behind the boat while people watch. sentence:  The person falls in the water, but stands again and continues doing water ski. sentence:  A boat appears in the river behind the person, while the person water ski. sentence:  The person falls again in the water, the people in the boat laugh and a man does thumbs up.