1 time. Exam standard: Candidates' departure mode and swimming mode are not limited. Candidates swim the whole course in the designated lane. Candidates can stand at the bottom of the pool when swimming, but they are not allowed to cross or walk at the bottom of the pool, pull the water route or interfere with others' swimming. Candidates are not allowed to use or wear any equipment conducive to speed, buoyancy and endurance. They must wear swimming caps and goggles. Everyone swims once during the exam. When the candidate reaches the finish line and touches the wall with his hand, the time stops and the score is recorded in seconds. Full score: 60 seconds for boys, 1 opportunity/person, 70 seconds for girls, 1 opportunity/person, and the project score: 15.