The only way to change the closed loop into a closed loop plus knot is to cut the string, tie the knot and then reseal the ends of the string together.

• 将没有扭结的封闭迴圈变成一个封闭迴圈加上扭结的唯一办法是切断弦，绑出扭结，再将弦的两端封起来。