1. Roller, pinyin: gǔn, is a cylindrical part that can rotate on the machine.

2. The main device on the roller [zhágǔn] rolling mill is a pair of rollers with opposite rotation directions, and a seam or hole with a certain shape is formed between the two rollers, and the billet passes through the seam or hole and is rolled into steel.

3. Roll roll [gǔngǔn] is a gangster. Describe the muddled life.