Qujiang Kangqiao School in Xi City may offer a swimming grading course, which is a good opportunity for students to learn swimming. Usually, it is enough for students to learn to swim in three years, but successful learning to swim depends on many factors, including students' interests, personal ability, practice frequency and coaches' teaching methods.

Here are some suggestions to help children learn to swim in three years:

1.** Active participation: * * Encourage children to actively participate in swimming lessons. Interest and motivation are one of the key factors in learning to swim. If children are interested in learning to swim, they are more likely to stick to it.

2.** Regular practice: * * Swimming is a sport that requires skills and needs regular practice. Encouraging children to practice swimming in their spare time outside the school swimming class can speed up their learning progress.

3.** Personalized guidance: * * If possible, consider providing personalized swimming guidance for children. One-on-one or group guidance can better meet children's learning needs.

4.** Safety first: * * Emphasize the safety of swimming. Make sure that children understand the basic safety principles of swimming, such as water depth, precautions during swimming and self-help methods in emergencies.

5.** Patience and encouragement: * * Swimming is a challenging skill, and children may encounter difficulties. Encourage them to be patient, believe in their own abilities, and don't let failure dampen their confidence.

6.** Supervision and support: * * The supervision and support of parents is also very important for children to learn swimming. Encourage children to take swimming lessons, participate in them in person, and provide them with necessary support.

In short, three years is usually enough time for children to learn to swim, provided that children are interested, actively participate, practice regularly and get appropriate guidance and support. In the case that the school provides graded swimming courses, children have the opportunity to gradually improve their swimming skills and finally master basic swimming skills.