咬定牙关

Explanation: Describe the determination and perseverance. 　　Source: Ming Wu Cheng-en, "Journey to the West," the elders insist that the fifty-fifth back teeth, the sound is not transparent. " 　　Examples: Li Kui whole body peeling off, ~, hand Nuoshuang Fu, Ho in the fly from the city to kill over. ★ "Water Margin" back to the sixth six